Introduce BrotliEncoder (#11256)

Motivation:
Currently, Netty only has BrotliDecoder which can decode Brotli encoded data. However, BrotliEncoder is missing which will encode normal data to Brotli encoded data.

Modification:
Added BrotliEncoder and CompressionOption

Result:
Fixes #6899.

Co-authored-by: Norman Maurer <norman_maurer@apple.com>

NOTICE.txt

@@ -254,3 +254,11 @@ This private header is also used by Apple's open source
     * license/LICENSE.dnsinfo.txt (Apple Public Source License 2.0)
   * HOMEPAGE:
     * https://www.opensource.apple.com/source/configd/configd-453.19/dnsinfo/dnsinfo.h
+
+This product optionally depends on 'Brotli4j', Brotli compression and
+decompression for Java., which can be obtained at:
+
+  * LICENSE:
+    * license/LICENSE.brotli4j.txt (Apache License 2.0)
+  * HOMEPAGE:
+    * https://github.com/hyperxpro/Brotli4j

codec-http/pom.xml

@@ -74,7 +74,7 @@
     <dependency>
       <groupId>com.aayushatharva.brotli4j</groupId>
       <artifactId>brotli4j</artifactId>
-      <scope>test</scope>
+      <optional>true</optional>
     </dependency>
     <dependency>
       <groupId>com.aayushatharva.brotli4j</groupId>

codec-http/src/main/java/io/netty/handler/codec/http/HttpContentCompressor.java

@@ -17,8 +17,15 @@ package io.netty.handler.codec.http;
 
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.embedded.EmbeddedChannel;
+import io.netty.handler.codec.compression.Brotli;
+import io.netty.handler.codec.compression.BrotliEncoder;
 import io.netty.handler.codec.compression.ZlibCodecFactory;
 import io.netty.handler.codec.compression.ZlibWrapper;
+import io.netty.handler.codec.compression.BrotliOptions;
+import io.netty.handler.codec.compression.CompressionOptions;
+import io.netty.handler.codec.compression.DeflateOptions;
+import io.netty.handler.codec.compression.GzipOptions;
+import io.netty.handler.codec.compression.StandardCompressionOptions;
 import io.netty.util.internal.ObjectUtil;
 
 /**
@@ -30,6 +37,11 @@ import io.netty.util.internal.ObjectUtil;
  */
 public class HttpContentCompressor extends HttpContentEncoder {
 
+    private final boolean supportsCompressionOptions;
+    private final BrotliOptions brotliOptions;
+    private final GzipOptions gzipOptions;
+    private final DeflateOptions deflateOptions;
+
     private final int compressionLevel;
     private final int windowBits;
     private final int memLevel;
@@ -53,6 +65,7 @@ public class HttpContentCompressor extends HttpContentEncoder {
      *        best compression.  {@code 0} means no compression.  The default
      *        compression level is {@code 6}.
      */
+    @Deprecated
     public HttpContentCompressor(int compressionLevel) {
         this(compressionLevel, 15, 8, 0);
     }
@@ -76,6 +89,7 @@ public class HttpContentCompressor extends HttpContentEncoder {
      *        memory.  Larger values result in better and faster compression
      *        at the expense of memory usage.  The default value is {@code 8}
      */
+    @Deprecated
     public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel) {
         this(compressionLevel, windowBits, memLevel, 0);
     }
@@ -103,11 +117,80 @@ public class HttpContentCompressor extends HttpContentEncoder {
      *        body exceeds the threshold. The value should be a non negative
      *        number. {@code 0} will enable compression for all responses.
      */
+    @Deprecated
     public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel, int contentSizeThreshold) {
         this.compressionLevel = ObjectUtil.checkInRange(compressionLevel, 0, 9, "compressionLevel");
         this.windowBits = ObjectUtil.checkInRange(windowBits, 9, 15, "windowBits");
         this.memLevel = ObjectUtil.checkInRange(memLevel, 1, 9, "memLevel");
         this.contentSizeThreshold = ObjectUtil.checkPositiveOrZero(contentSizeThreshold, "contentSizeThreshold");
+        this.brotliOptions = null;
+        this.gzipOptions = null;
+        this.deflateOptions = null;
+        supportsCompressionOptions = false;
+    }
+
+    /**
+     * Create a new {@link HttpContentCompressor} Instance with specified
+     * {@link CompressionOptions}s and contentSizeThreshold set to {@code 0}
+     *
+     * @param compressionOptions {@link CompressionOptions} or {@code null} if the default
+     *        should be used.
+     */
+    public HttpContentCompressor(CompressionOptions... compressionOptions) {
+        this(0, compressionOptions);
+    }
+
+    /**
+     * Create a new {@link HttpContentCompressor} instance with specified
+     * {@link CompressionOptions}s
+     *
+     * @param contentSizeThreshold
+     *        The response body is compressed when the size of the response
+     *        body exceeds the threshold. The value should be a non negative
+     *        number. {@code 0} will enable compression for all responses.
+     * @param compressionOptions {@link CompressionOptions} or {@code null}
+     *        if the default should be used.
+     */
+    public HttpContentCompressor(int contentSizeThreshold, CompressionOptions... compressionOptions) {
+        this.contentSizeThreshold = ObjectUtil.checkPositiveOrZero(contentSizeThreshold, "contentSizeThreshold");
+        BrotliOptions brotliOptions = null;
+        GzipOptions gzipOptions = null;
+        DeflateOptions deflateOptions = null;
+        if (compressionOptions == null || compressionOptions.length == 0) {
+            brotliOptions = StandardCompressionOptions.brotli();
+            gzipOptions = StandardCompressionOptions.gzip();
+            deflateOptions = StandardCompressionOptions.deflate();
+        } else {
+            ObjectUtil.deepCheckNotNull("compressionOptionsIterable", compressionOptions);
+            for (CompressionOptions compressionOption : compressionOptions) {
+                if (compressionOption instanceof BrotliOptions) {
+                    brotliOptions = (BrotliOptions) compressionOption;
+                } else if (compressionOption instanceof GzipOptions) {
+                    gzipOptions = (GzipOptions) compressionOption;
+                } else if (compressionOption instanceof DeflateOptions) {
+                    deflateOptions = (DeflateOptions) compressionOption;
+                } else {
+                    throw new IllegalArgumentException("Unsupported " + CompressionOptions.class.getSimpleName() +
+                            ": " + compressionOption);
+                }
+            }
+            if (brotliOptions == null) {
+                brotliOptions = StandardCompressionOptions.brotli();
+            }
+            if (gzipOptions == null) {
+                gzipOptions = StandardCompressionOptions.gzip();
+            }
+            if (deflateOptions == null) {
+                deflateOptions = StandardCompressionOptions.deflate();
+            }
+        }
+        this.brotliOptions = brotliOptions;
+        this.gzipOptions = gzipOptions;
+        this.deflateOptions = deflateOptions;
+        this.compressionLevel = -1;
+        this.windowBits = -1;
+        this.memLevel = -1;
+        supportsCompressionOptions = true;
     }
 
     @Override
@@ -131,30 +214,109 @@ public class HttpContentCompressor extends HttpContentEncoder {
             return null;
         }
 
-        ZlibWrapper wrapper = determineWrapper(acceptEncoding);
+        if (supportsCompressionOptions) {
-        if (wrapper == null) {
+            String targetContentEncoding = determineEncoding(acceptEncoding);
-            return null;
+            if (targetContentEncoding == null) {
-        }
+                return null;
+            }
 
-        String targetContentEncoding;
+            if (targetContentEncoding.equals("gzip")) {
-        switch (wrapper) {
+                return new Result(targetContentEncoding,
-        case GZIP:
+                        new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
-            targetContentEncoding = "gzip";
+                                ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(
-            break;
+                                ZlibWrapper.GZIP, gzipOptions.compressionLevel()
-        case ZLIB:
+                                , gzipOptions.windowBits(), gzipOptions.memLevel())));
-            targetContentEncoding = "deflate";
+            }
-            break;
+            if (targetContentEncoding.equals("deflate")) {
-        default:
+                return new Result(targetContentEncoding,
+                        new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+                                ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(
+                                ZlibWrapper.ZLIB, deflateOptions.compressionLevel(),
+                                deflateOptions.windowBits(), deflateOptions.memLevel())));
+            }
+            if (targetContentEncoding.equals("br")) {
+                return new Result(targetContentEncoding,
+                        new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+                                ctx.channel().config(), new BrotliEncoder(brotliOptions.parameters())));
+            }
             throw new Error();
-        }
+        } else {
+            ZlibWrapper wrapper = determineWrapper(acceptEncoding);
+            if (wrapper == null) {
+                return null;
+            }
 
-        return new Result(
+            String targetContentEncoding;
-                targetContentEncoding,
+            switch (wrapper) {
-                new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+                case GZIP:
-                        ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(
+                    targetContentEncoding = "gzip";
-                        wrapper, compressionLevel, windowBits, memLevel)));
+                    break;
+                case ZLIB:
+                    targetContentEncoding = "deflate";
+                    break;
+                default:
+                    throw new Error();
+            }
+
+            return new Result(
+                    targetContentEncoding,
+                    new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+                            ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(
+                            wrapper, compressionLevel, windowBits, memLevel)));
+        }
     }
 
+    @SuppressWarnings("FloatingPointEquality")
+    protected String determineEncoding(String acceptEncoding) {
+        float starQ = -1.0f;
+        float brQ = -1.0f;
+        float gzipQ = -1.0f;
+        float deflateQ = -1.0f;
+        for (String encoding : acceptEncoding.split(",")) {
+            float q = 1.0f;
+            int equalsPos = encoding.indexOf('=');
+            if (equalsPos != -1) {
+                try {
+                    q = Float.parseFloat(encoding.substring(equalsPos + 1));
+                } catch (NumberFormatException e) {
+                    // Ignore encoding
+                    q = 0.0f;
+                }
+            }
+            if (encoding.contains("*")) {
+                starQ = q;
+            } else if (encoding.contains("br") && q > brQ) {
+                brQ = q;
+            } else if (encoding.contains("gzip") && q > gzipQ) {
+                gzipQ = q;
+            } else if (encoding.contains("deflate") && q > deflateQ) {
+                deflateQ = q;
+            }
+        }
+        if (brQ > 0.0f || gzipQ > 0.0f || deflateQ > 0.0f) {
+            if (brQ != -1.0f && brQ >= gzipQ) {
+                return Brotli.isAvailable() ? "br" : null;
+            } else if (gzipQ != -1.0f && gzipQ >= deflateQ) {
+                return "gzip";
+            } else if (deflateQ != -1.0f) {
+                return "deflate";
+            }
+        }
+        if (starQ > 0.0f) {
+            if (brQ == -1.0f) {
+                return Brotli.isAvailable() ? "br" : null;
+            }
+            if (gzipQ == -1.0f) {
+                return "gzip";
+            }
+            if (deflateQ == -1.0f) {
+                return "deflate";
+            }
+        }
+        return null;
+    }
+
+    @Deprecated
     @SuppressWarnings("FloatingPointEquality")
     protected ZlibWrapper determineWrapper(String acceptEncoding) {
         float starQ = -1.0f;

codec-http/src/test/java/io/netty/handler/codec/http/BrotliContentCompressorTest.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2021 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.http;
+
+import io.netty.channel.embedded.EmbeddedChannel;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.CoreMatchers.instanceOf;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.CoreMatchers.nullValue;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+
+class BrotliContentCompressorTest {
+
+    @Test
+    void testGetTargetContentEncoding() {
+        HttpContentCompressor compressor = new HttpContentCompressor();
+
+        String[] tests = {
+                // Accept-Encoding -> Content-Encoding
+                "", null,
+                "*", "br",
+                "*;q=0.0", null,
+                "br", "br",
+                "compress, br;q=0.5", "br",
+                "br; q=0.5, identity", "br",
+                "br; q=0, deflate", "br",
+        };
+        for (int i = 0; i < tests.length; i += 2) {
+            String acceptEncoding = tests[i];
+            String contentEncoding = tests[i + 1];
+            String targetEncoding = compressor.determineEncoding(acceptEncoding);
+            assertEquals(contentEncoding, targetEncoding);
+        }
+    }
+
+    @Test
+    void testAcceptEncodingHttpRequest() {
+        EmbeddedChannel ch = new EmbeddedChannel(new HttpContentCompressor(null));
+        ch.writeInbound(newRequest());
+        FullHttpRequest fullHttpRequest = ch.readInbound();
+        fullHttpRequest.release();
+
+        HttpResponse res = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
+        res.headers().set(HttpHeaderNames.TRANSFER_ENCODING, HttpHeaderValues.CHUNKED);
+        ch.writeOutbound(res);
+
+        assertEncodedResponse(ch);
+
+        assertTrue(ch.close().isSuccess());
+    }
+
+    private static void assertEncodedResponse(EmbeddedChannel ch) {
+        Object o = ch.readOutbound();
+        assertThat(o, is(instanceOf(HttpResponse.class)));
+
+        assertEncodedResponse((HttpResponse) o);
+    }
+
+    private static void assertEncodedResponse(HttpResponse res) {
+        assertThat(res, is(not(instanceOf(HttpContent.class))));
+        assertThat(res.headers().get(HttpHeaderNames.TRANSFER_ENCODING), is("chunked"));
+        assertThat(res.headers().get(HttpHeaderNames.CONTENT_LENGTH), is(nullValue()));
+        assertThat(res.headers().get(HttpHeaderNames.CONTENT_ENCODING), is("br"));
+    }
+
+    private static FullHttpRequest newRequest() {
+        FullHttpRequest req = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET, "/");
+        req.headers().set(HttpHeaderNames.ACCEPT_ENCODING, "br, gzip, deflate");
+        return req;
+    }
+}

codec-http/src/test/java/io/netty/handler/codec/http/HttpContentCompressorTest.java

@@ -778,6 +778,7 @@ public class HttpContentCompressorTest {
         assertThat(res.headers().get(HttpHeaderNames.CONTENT_LENGTH), is(nullValue()));
         assertThat(res.headers().get(HttpHeaderNames.CONTENT_ENCODING), is("gzip"));
     }
+
     private static void assertAssembledEncodedResponse(EmbeddedChannel ch) {
         Object o = ch.readOutbound();
         assertThat(o, is(instanceOf(AssembledHttpResponse.class)));

codec-http2/pom.xml

@@ -88,6 +88,11 @@
       <scope>test</scope>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>com.aayushatharva.brotli4j</groupId>
+      <artifactId>brotli4j</artifactId>
+      <optional>true</optional>
+    </dependency>
   </dependencies>
 </project>
 

codec-http2/src/main/java/io/netty/handler/codec/http2/CompressorHttp2ConnectionEncoder.java

@@ -21,14 +21,21 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPromise;
 import io.netty.channel.embedded.EmbeddedChannel;
 import io.netty.handler.codec.ByteToMessageDecoder;
+import io.netty.handler.codec.compression.BrotliEncoder;
 import io.netty.handler.codec.compression.ZlibCodecFactory;
 import io.netty.handler.codec.compression.ZlibWrapper;
+import io.netty.handler.codec.compression.BrotliOptions;
+import io.netty.handler.codec.compression.CompressionOptions;
+import io.netty.handler.codec.compression.DeflateOptions;
+import io.netty.handler.codec.compression.GzipOptions;
+import io.netty.handler.codec.compression.StandardCompressionOptions;
 import io.netty.util.concurrent.PromiseCombiner;
 import io.netty.util.internal.ObjectUtil;
 import io.netty.util.internal.UnstableApi;
 
 import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_ENCODING;
 import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_LENGTH;
+import static io.netty.handler.codec.http.HttpHeaderValues.BR;
 import static io.netty.handler.codec.http.HttpHeaderValues.DEFLATE;
 import static io.netty.handler.codec.http.HttpHeaderValues.GZIP;
 import static io.netty.handler.codec.http.HttpHeaderValues.IDENTITY;
@@ -41,19 +48,35 @@ import static io.netty.handler.codec.http.HttpHeaderValues.X_GZIP;
  */
 @UnstableApi
 public class CompressorHttp2ConnectionEncoder extends DecoratingHttp2ConnectionEncoder {
+    // We cannot remove this because it'll be breaking change
     public static final int DEFAULT_COMPRESSION_LEVEL = 6;
     public static final int DEFAULT_WINDOW_BITS = 15;
     public static final int DEFAULT_MEM_LEVEL = 8;
 
-    private final int compressionLevel;
+    private int compressionLevel;
-    private final int windowBits;
+    private int windowBits;
-    private final int memLevel;
+    private int memLevel;
     private final Http2Connection.PropertyKey propertyKey;
 
+    private final boolean supportsCompressionOptions;
+
+    private BrotliOptions brotliOptions;
+    private GzipOptions gzipCompressionOptions;
+    private DeflateOptions deflateOptions;
+
+    /**
+     * Create a new {@link CompressorHttp2ConnectionEncoder} instance
+     * with default implementation of {@link StandardCompressionOptions}
+     */
     public CompressorHttp2ConnectionEncoder(Http2ConnectionEncoder delegate) {
-        this(delegate, DEFAULT_COMPRESSION_LEVEL, DEFAULT_WINDOW_BITS, DEFAULT_MEM_LEVEL);
+        this(delegate, StandardCompressionOptions.brotli(), StandardCompressionOptions.gzip(),
+                StandardCompressionOptions.deflate());
     }
 
+    /**
+     * Create a new {@link CompressorHttp2ConnectionEncoder} instance
+     */
+    @Deprecated
     public CompressorHttp2ConnectionEncoder(Http2ConnectionEncoder delegate, int compressionLevel, int windowBits,
                                             int memLevel) {
         super(delegate);
@@ -71,6 +94,45 @@ public class CompressorHttp2ConnectionEncoder extends DecoratingHttp2ConnectionE
                 }
             }
         });
+
+        supportsCompressionOptions = false;
+    }
+
+    /**
+     * Create a new {@link CompressorHttp2ConnectionEncoder} with
+     * specified {@link StandardCompressionOptions}
+     */
+    public CompressorHttp2ConnectionEncoder(Http2ConnectionEncoder delegate,
+                                            CompressionOptions... compressionOptionsArgs) {
+        super(delegate);
+        ObjectUtil.checkNotNull(compressionOptionsArgs, "CompressionOptions");
+        ObjectUtil.deepCheckNotNull("CompressionOptions", compressionOptionsArgs);
+
+        for (CompressionOptions compressionOptions : compressionOptionsArgs) {
+            if (compressionOptions instanceof BrotliOptions) {
+                brotliOptions = (BrotliOptions) compressionOptions;
+            } else if (compressionOptions instanceof GzipOptions) {
+                gzipCompressionOptions = (GzipOptions) compressionOptions;
+            } else if (compressionOptions instanceof DeflateOptions) {
+                deflateOptions = (DeflateOptions) compressionOptions;
+            } else {
+                throw new IllegalArgumentException("Unsupported " + CompressionOptions.class.getSimpleName() +
+                        ": " + compressionOptions);
+            }
+        }
+
+        supportsCompressionOptions = true;
+
+        propertyKey = connection().newKey();
+        connection().addListener(new Http2ConnectionAdapter() {
+            @Override
+            public void onStreamRemoved(Http2Stream stream) {
+                final EmbeddedChannel compressor = stream.getProperty(propertyKey);
+                if (compressor != null) {
+                    cleanup(stream, compressor);
+                }
+            }
+        });
     }
 
     @Override
@@ -190,6 +252,10 @@ public class CompressorHttp2ConnectionEncoder extends DecoratingHttp2ConnectionE
         if (DEFLATE.contentEqualsIgnoreCase(contentEncoding) || X_DEFLATE.contentEqualsIgnoreCase(contentEncoding)) {
             return newCompressionChannel(ctx, ZlibWrapper.ZLIB);
         }
+        if (brotliOptions != null && BR.contentEqualsIgnoreCase(contentEncoding)) {
+            return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+                    ctx.channel().config(), new BrotliEncoder(brotliOptions.parameters()));
+        }
         // 'identity' or unsupported
         return null;
     }
@@ -212,9 +278,25 @@ public class CompressorHttp2ConnectionEncoder extends DecoratingHttp2ConnectionE
      * @param wrapper Defines what type of encoder should be used
      */
     private EmbeddedChannel newCompressionChannel(final ChannelHandlerContext ctx, ZlibWrapper wrapper) {
-        return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+        if (supportsCompressionOptions) {
-                ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(wrapper, compressionLevel, windowBits,
+            if (wrapper == ZlibWrapper.GZIP && gzipCompressionOptions != null) {
-                memLevel));
+                return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+                        ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(wrapper,
+                        gzipCompressionOptions.compressionLevel(), gzipCompressionOptions.windowBits(),
+                        gzipCompressionOptions.memLevel()));
+            } else if (wrapper == ZlibWrapper.ZLIB && deflateOptions != null) {
+                return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+                        ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(wrapper,
+                        deflateOptions.compressionLevel(), deflateOptions.windowBits(),
+                        deflateOptions.memLevel()));
+            } else {
+                throw new IllegalArgumentException("Unsupported ZlibWrapper: " + wrapper);
+            }
+        } else {
+            return new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
+                    ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(wrapper, compressionLevel, windowBits,
+                    memLevel));
+        }
     }
 
     /**

codec-http2/src/test/java/io/netty/handler/codec/http2/DataCompressionHttp2Test.java

@@ -235,6 +235,54 @@ public class DataCompressionHttp2Test {
         }
     }
 
+    @Test
+    public void brotliEncodingSingleEmptyMessage() throws Exception {
+        final String text = "";
+        final ByteBuf data = Unpooled.copiedBuffer(text.getBytes());
+        bootstrapEnv(data.readableBytes());
+        try {
+            final Http2Headers headers = new DefaultHttp2Headers().method(POST).path(PATH)
+                    .set(HttpHeaderNames.CONTENT_ENCODING, HttpHeaderValues.BR);
+
+            runInChannel(clientChannel, new Http2Runnable() {
+                @Override
+                public void run() throws Http2Exception {
+                    clientEncoder.writeHeaders(ctxClient(), 3, headers, 0, false, newPromiseClient());
+                    clientEncoder.writeData(ctxClient(), 3, data.retain(), 0, true, newPromiseClient());
+                    clientHandler.flush(ctxClient());
+                }
+            });
+            awaitServer();
+            assertEquals(text, serverOut.toString(CharsetUtil.UTF_8.name()));
+        } finally {
+            data.release();
+        }
+    }
+
+    @Test
+    public void brotliEncodingSingleMessage() throws Exception {
+        final String text = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbbbbbbbbbbbbbbbbbbbbbbbbbbccccccccccccccccccccccc";
+        final ByteBuf data = Unpooled.copiedBuffer(text.getBytes(CharsetUtil.UTF_8.name()));
+        bootstrapEnv(data.readableBytes());
+        try {
+            final Http2Headers headers = new DefaultHttp2Headers().method(POST).path(PATH)
+                    .set(HttpHeaderNames.CONTENT_ENCODING, HttpHeaderValues.BR);
+
+            runInChannel(clientChannel, new Http2Runnable() {
+                @Override
+                public void run() throws Http2Exception {
+                    clientEncoder.writeHeaders(ctxClient(), 3, headers, 0, false, newPromiseClient());
+                    clientEncoder.writeData(ctxClient(), 3, data.retain(), 0, true, newPromiseClient());
+                    clientHandler.flush(ctxClient());
+                }
+            });
+            awaitServer();
+            assertEquals(text, serverOut.toString(CharsetUtil.UTF_8.name()));
+        } finally {
+            data.release();
+        }
+    }
+
     @Test
     public void deflateEncodingWriteLargeMessage() throws Exception {
         final int BUFFER_SIZE = 1 << 12;

codec/src/main/java/io/netty/handler/codec/compression/Brotli.java

@@ -25,6 +25,7 @@ public final class Brotli {
 
     private static final InternalLogger logger = InternalLoggerFactory.getInstance(Brotli.class);
     private static final ClassNotFoundException CNFE;
+    private static Throwable cause;
 
     static {
         ClassNotFoundException cnfe = null;
@@ -42,7 +43,7 @@ public final class Brotli {
 
         // If in the classpath, try to load the native library and initialize brotli4j.
         if (cnfe == null) {
-            Throwable cause = Brotli4jLoader.getUnavailabilityCause();
+            cause = Brotli4jLoader.getUnavailabilityCause();
             if (cause != null) {
                 logger.debug("Failed to load brotli4j; Brotli support will be unavailable.", cause);
             }
@@ -70,6 +71,13 @@ public final class Brotli {
         Brotli4jLoader.ensureAvailability();
     }
 
+    /**
+     * Returns {@link Throwable} of unavailability cause
+     */
+    public static Throwable cause() {
+        return cause;
+    }
+
     private Brotli() {
     }
 }

codec/src/main/java/io/netty/handler/codec/compression/BrotliEncoder.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2021 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.compression;
+
+import com.aayushatharva.brotli4j.encoder.Encoder;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
+import io.netty.buffer.Unpooled;
+import io.netty.channel.ChannelHandler;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.MessageToByteEncoder;
+import io.netty.util.ReferenceCountUtil;
+import io.netty.util.internal.ObjectUtil;
+
+/**
+ * Compress a {@link ByteBuf} with the brotli format.
+ *
+ * See <a href="https://github.com/google/brotli">brotli</a>.
+ */
+@ChannelHandler.Sharable
+public final class BrotliEncoder extends MessageToByteEncoder<ByteBuf> {
+
+    private final Encoder.Parameters parameters;
+
+    /**
+     * Create a new {@link BrotliEncoder} Instance
+     * with {@link Encoder.Parameters#setQuality(int)} set to 4
+     * and {@link Encoder.Parameters#setMode(Encoder.Mode)} set to {@link Encoder.Mode#TEXT}
+     */
+    public BrotliEncoder() {
+        this(BrotliOptions.DEFAULT);
+    }
+
+    /**
+     * Create a new {@link BrotliEncoder} Instance
+     *
+     * @param parameters {@link Encoder.Parameters} Instance
+     */
+    public BrotliEncoder(Encoder.Parameters parameters) {
+        this.parameters = ObjectUtil.checkNotNull(parameters, "Parameters");
+    }
+
+    /**
+     * Create a new {@link BrotliEncoder} Instance
+     *
+     * @param brotliOptions {@link BrotliOptions} to use.
+     */
+    public BrotliEncoder(BrotliOptions brotliOptions) {
+        this(brotliOptions.parameters());
+    }
+
+    @Override
+    protected void encode(ChannelHandlerContext ctx, ByteBuf msg, ByteBuf out) throws Exception {
+        // NO-OP
+    }
+
+    @Override
+    protected ByteBuf allocateBuffer(ChannelHandlerContext ctx, ByteBuf msg, boolean preferDirect) throws Exception {
+        // If ByteBuf is unreadable, then return EMPTY_BUFFER.
+        if (!msg.isReadable()) {
+            return Unpooled.EMPTY_BUFFER;
+        }
+
+        try {
+            byte[] uncompressed = ByteBufUtil.getBytes(msg, msg.readerIndex(), msg.readableBytes(), false);
+            byte[] compressed = Encoder.compress(uncompressed, parameters);
+            if (preferDirect) {
+                ByteBuf out = ctx.alloc().ioBuffer(compressed.length);
+                out.writeBytes(compressed);
+                return out;
+            } else {
+                return Unpooled.wrappedBuffer(compressed);
+            }
+        } catch (Exception e) {
+            ReferenceCountUtil.release(msg);
+            throw e;
+        }
+    }
+}

codec/src/main/java/io/netty/handler/codec/compression/BrotliOptions.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2021 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.compression;
+
+import com.aayushatharva.brotli4j.encoder.Encoder;
+import io.netty.util.internal.ObjectUtil;
+
+/**
+ * {@link BrotliOptions} holds {@link Encoder.Parameters} for
+ * Brotli compression.
+ */
+public final class BrotliOptions implements CompressionOptions {
+
+    private final Encoder.Parameters parameters;
+
+    /**
+     * Default implementation of {@link BrotliOptions} with{@link Encoder.Parameters#setQuality(int)} set to 4
+     * and {@link Encoder.Parameters#setMode(Encoder.Mode)} set to {@link Encoder.Mode#TEXT}
+     */
+    static final BrotliOptions DEFAULT = new BrotliOptions(
+            new Encoder.Parameters().setQuality(4).setMode(Encoder.Mode.TEXT)
+    );
+
+    /**
+     * Create a new {@link BrotliOptions}
+     *
+     * @param parameters {@link Encoder.Parameters} Instance
+     * @throws NullPointerException If {@link Encoder.Parameters} is {@code null}
+     */
+    BrotliOptions(Encoder.Parameters parameters) {
+        this.parameters = ObjectUtil.checkNotNull(parameters, "Parameters");
+
+        if (!Brotli.isAvailable()) {
+            throw new IllegalStateException("Brotli is not available", Brotli.cause());
+        }
+    }
+
+    public Encoder.Parameters parameters() {
+        return parameters;
+    }
+}

codec/src/main/java/io/netty/handler/codec/compression/CompressionOptions.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2021 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.compression;
+
+/**
+ * {@link CompressionOptions} provides compression options for
+ * various types of compressor types, like Brotli.
+ *
+ * A {@link CompressionOptions} instance is thread-safe
+ * and should be shared between multiple instances of Compressor.
+ */
+public interface CompressionOptions {
+    // Empty
+}

codec/src/main/java/io/netty/handler/codec/compression/DeflateOptions.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2021 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.compression;
+
+import io.netty.util.internal.ObjectUtil;
+
+/**
+ * {@link DeflateOptions} holds {@link #compressionLevel()},
+ * {@link #memLevel()} and {@link #windowBits()} for Deflate compression.
+ */
+public class DeflateOptions implements CompressionOptions {
+
+    private final int compressionLevel;
+    private final int windowBits;
+    private final int memLevel;
+
+    /**
+     * Default implementation of {@link DeflateOptions} with
+     * {@link #compressionLevel} set to 6, {@link #windowBits} set to 15
+     * and {@link #memLevel} set to 8.
+     */
+    static final DeflateOptions DEFAULT = new DeflateOptions(
+            6, 15, 8
+    );
+
+    /**
+     * Create a new {@link DeflateOptions} Instance
+     *
+     * @param compressionLevel {@code 1} yields the fastest compression and {@code 9} yields the
+     *                         best compression.  {@code 0} means no compression.  The default
+     *                         compression level is {@code 6}.
+     *
+     * @param windowBits       The base two logarithm of the size of the history buffer.  The
+     *                         value should be in the range {@code 9} to {@code 15} inclusive.
+     *                         Larger values result in better compression at the expense of
+     *                         memory usage.  The default value is {@code 15}.
+     *
+     * @param memLevel         How much memory should be allocated for the internal compression
+     *                         state.  {@code 1} uses minimum memory and {@code 9} uses maximum
+     *                         memory.  Larger values result in better and faster compression
+     *                         at the expense of memory usage.  The default value is {@code 8}
+     */
+    DeflateOptions(int compressionLevel, int windowBits, int memLevel) {
+        this.compressionLevel = ObjectUtil.checkInRange(compressionLevel, 0, 9, "compressionLevel");
+        this.windowBits = ObjectUtil.checkInRange(windowBits, 9, 15, "windowBits");
+        this.memLevel = ObjectUtil.checkInRange(memLevel, 1, 9, "memLevel");
+    }
+
+    public int compressionLevel() {
+        return compressionLevel;
+    }
+
+    public int windowBits() {
+        return windowBits;
+    }
+
+    public int memLevel() {
+        return memLevel;
+    }
+}

codec/src/main/java/io/netty/handler/codec/compression/GzipOptions.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2021 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.compression;
+
+/**
+ * {@link GzipOptions} holds {@link #compressionLevel()},
+ * {@link #memLevel()} and {@link #windowBits()} for Gzip compression.
+ * This class is an extension of {@link DeflateOptions}
+ */
+public final class GzipOptions extends DeflateOptions {
+
+    /**
+     * Default implementation of {@link GzipOptions} with
+     * {@link #compressionLevel()} set to 6, {@link #windowBits()} set to 15
+     * and {@link #memLevel()} set to 8.
+     */
+    static final GzipOptions DEFAULT = new GzipOptions(
+            6, 15, 8
+    );
+
+    /**
+     * Create a new {@link GzipOptions} Instance
+     *
+     * @param compressionLevel {@code 1} yields the fastest compression and {@code 9} yields the
+     *                         best compression.  {@code 0} means no compression.  The default
+     *                         compression level is {@code 6}.
+     *
+     * @param windowBits       The base two logarithm of the size of the history buffer.  The
+     *                         value should be in the range {@code 9} to {@code 15} inclusive.
+     *                         Larger values result in better compression at the expense of
+     *                         memory usage.  The default value is {@code 15}.
+     *
+     * @param memLevel         How much memory should be allocated for the internal compression
+     *                         state.  {@code 1} uses minimum memory and {@code 9} uses maximum
+     *                         memory.  Larger values result in better and faster compression
+     *                         at the expense of memory usage.  The default value is {@code 8}
+     */
+    GzipOptions(int compressionLevel, int windowBits, int memLevel) {
+        super(compressionLevel, windowBits, memLevel);
+    }
+}

codec/src/main/java/io/netty/handler/codec/compression/StandardCompressionOptions.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2021 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.compression;
+
+import com.aayushatharva.brotli4j.encoder.Encoder;
+
+/**
+ * Standard Compression Options for {@link BrotliOptions},
+ * {@link GzipOptions} and {@link DeflateOptions}
+ */
+public final class StandardCompressionOptions {
+
+    private StandardCompressionOptions() {
+        // Prevent outside initialization
+    }
+
+    /**
+     * @see BrotliOptions#DEFAULT
+     */
+    public static BrotliOptions brotli() {
+        return BrotliOptions.DEFAULT;
+    }
+
+    /**
+     * @see BrotliOptions#BrotliOptions(Encoder.Parameters)
+     */
+    public static BrotliOptions brotli(Encoder.Parameters parameters) {
+        return new BrotliOptions(parameters);
+    }
+
+    /**
+     * @see GzipOptions#DEFAULT
+     */
+    public static GzipOptions gzip() {
+        return GzipOptions.DEFAULT;
+    }
+
+    /**
+     * @see GzipOptions#GzipOptions(int, int, int)
+     */
+    public static GzipOptions gzip(int compressionLevel, int windowBits, int memLevel) {
+        return new GzipOptions(compressionLevel, windowBits, memLevel);
+    }
+
+    /**
+     * @see DeflateOptions#DEFAULT
+     */
+    public static DeflateOptions deflate() {
+        return DeflateOptions.DEFAULT;
+    }
+
+    /**
+     * @see DeflateOptions#DeflateOptions(int, int, int)
+     */
+    public static DeflateOptions deflate(int compressionLevel, int windowBits, int memLevel) {
+        return new DeflateOptions(compressionLevel, windowBits, memLevel);
+    }
+}

codec/src/test/java/io/netty/handler/codec/compression/BrotliDecoderTest.java

@@ -136,7 +136,7 @@ public class BrotliDecoderTest {
         decompressed.release();
     }
 
-  private void testDecompressionOfBatchedFlow(final ByteBuf expected, final ByteBuf data) {
+    private void testDecompressionOfBatchedFlow(final ByteBuf expected, final ByteBuf data) {
         final int compressedLength = data.readableBytes();
         int written = 0, length = RANDOM.nextInt(100);
         while (written + length < compressedLength) {
@@ -155,7 +155,7 @@ public class BrotliDecoderTest {
         data.release();
     }
 
-  private static ByteBuf readDecompressed(final EmbeddedChannel channel) {
+    private static ByteBuf readDecompressed(final EmbeddedChannel channel) {
         CompositeByteBuf decompressed = Unpooled.compositeBuffer();
         ByteBuf msg;
         while ((msg = channel.readInbound()) != null) {

codec/src/test/java/io/netty/handler/codec/compression/BrotliEncoderTest.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2021 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.codec.compression;
+
+import com.aayushatharva.brotli4j.decoder.Decoder;
+import com.aayushatharva.brotli4j.decoder.DecoderJNI;
+import com.aayushatharva.brotli4j.decoder.DirectDecompress;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.CompositeByteBuf;
+import io.netty.buffer.Unpooled;
+import io.netty.channel.embedded.EmbeddedChannel;
+import io.netty.util.internal.PlatformDependent;
+import org.junit.jupiter.api.condition.DisabledIf;
+
+@DisabledIf(value = "isNotSupported", disabledReason = "Brotli is not supported on this platform")
+public class BrotliEncoderTest extends AbstractEncoderTest {
+
+    static {
+        try {
+            Brotli.ensureAvailability();
+        } catch (Throwable throwable) {
+            throw new ExceptionInInitializerError(throwable);
+        }
+    }
+
+    @Override
+    public EmbeddedChannel createChannel() {
+        return new EmbeddedChannel(new BrotliEncoder());
+    }
+
+    @Override
+    protected ByteBuf decompress(ByteBuf compressed, int originalLength) throws Exception {
+        byte[] compressedArray = new byte[compressed.readableBytes()];
+        compressed.readBytes(compressedArray);
+        compressed.release();
+
+        DirectDecompress decompress = Decoder.decompress(compressedArray);
+        if (decompress.getResultStatus() == DecoderJNI.Status.ERROR) {
+            throw new DecompressionException("Brotli stream corrupted");
+        }
+
+        byte[] decompressed = decompress.getDecompressedData();
+        return Unpooled.wrappedBuffer(decompressed);
+    }
+
+    @Override
+    protected ByteBuf readDecompressed(final int dataLength) throws Exception {
+        CompositeByteBuf decompressed = Unpooled.compositeBuffer();
+        ByteBuf msg;
+        while ((msg = channel.readOutbound()) != null) {
+            if (msg.isReadable()) {
+                decompressed.addComponent(true, decompress(msg, -1));
+            } else {
+                msg.release();
+            }
+        }
+        return decompressed;
+    }
+
+    static boolean isNotSupported() {
+        return (PlatformDependent.isOsx() || PlatformDependent.isWindows())
+                && "aarch_64".equals(PlatformDependent.normalizedArch());
+    }
+}

common/src/main/java/io/netty/util/internal/ObjectUtil.java

@@ -41,6 +41,26 @@ public final class ObjectUtil {
         return arg;
     }
 
+    /**
+     * Check that the given varargs is not null and does not contain elements
+     * null elements.
+     *
+     * If it is, throws {@link NullPointerException}.
+     * Otherwise, returns the argument.
+     */
+    public static <T> T[] deepCheckNotNull(String text, T... varargs) {
+        if (varargs == null) {
+            throw new NullPointerException(text);
+        }
+
+        for (T element : varargs) {
+            if (element == null) {
+                throw new NullPointerException(text);
+            }
+        }
+        return varargs;
+    }
+
     /**
      * Checks that the given argument is not null. If it is, throws {@link IllegalArgumentException}.
      * Otherwise, returns the argument.

license/LICENSE.brotli4j.txt

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        https://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       https://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.