Next round of cleanup of http2 codec

Motivation:
Bring the http2 codec more inline with the rest of Netty's code-base.

Modifications:

- Add null checks in constructors
- Move private static methods into inner-classes where they are used
- Use getBytes(CharsetUtil.UTf8)

Result:
More consistent code-base

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/DefaultHttp2Headers.java

@@ -35,8 +35,8 @@ public final class DefaultHttp2Headers extends Http2Headers {
     private final HeaderEntry head;
 
     private DefaultHttp2Headers(Builder builder) {
-        this.entries = builder.entries;
+        entries = builder.entries;
-        this.head = builder.head;
+        head = builder.head;
     }
 
     @Override
@@ -126,7 +126,7 @@ public final class DefaultHttp2Headers extends Http2Headers {
     }
 
     /**
-     * Builds instances of {@link DefaultHttp2Header}.
+     * Builds instances of {@link DefaultHttp2Headers}.
      */
     public static class Builder {
         private HeaderEntry[] entries;
@@ -344,6 +344,52 @@ public final class DefaultHttp2Headers extends Http2Headers {
             }
             return value.toString();
         }
+
+        /**
+         * Validate a HTTP2 header value. Does not validate max length.
+         */
+        private static void validateHeaderValue(String value) {
+            if (value == null) {
+                throw new NullPointerException("value");
+            }
+            for (int i = 0; i < value.length(); i ++) {
+                char c = value.charAt(i);
+                if (c == 0) {
+                    throw new IllegalArgumentException(
+                            "value contains null character: " + value);
+                }
+            }
+        }
+
+        /**
+         * Validate a HTTP2 header name.
+         */
+        private static void validateHeaderName(String name) {
+            if (name == null) {
+                throw new NullPointerException("name");
+            }
+            if (name.isEmpty()) {
+                throw new IllegalArgumentException(
+                        "name cannot be length zero");
+            }
+            // Since name may only contain ascii characters, for valid names
+            // name.length() returns the number of bytes when UTF-8 encoded.
+            if (name.length() > MAX_VALUE_LENGTH) {
+                throw new IllegalArgumentException(
+                        "name exceeds allowable length: " + name);
+            }
+            for (int i = 0; i < name.length(); i ++) {
+                char c = name.charAt(i);
+                if (c == 0) {
+                    throw new IllegalArgumentException(
+                            "name contains null character: " + name);
+                }
+                if (c > 127) {
+                    throw new IllegalArgumentException(
+                            "name contains non-ascii character: " + name);
+                }
+            }
+        }
     }
 
     private static int hash(String name) {
@@ -393,52 +439,6 @@ public final class DefaultHttp2Headers extends Http2Headers {
         return hash % BUCKET_SIZE;
     }
 
-    /**
-     * Validate a HTTP2 header name.
-     */
-    private static void validateHeaderName(String name) {
-        if (name == null) {
-            throw new NullPointerException("name");
-        }
-        if (name.isEmpty()) {
-            throw new IllegalArgumentException(
-                    "name cannot be length zero");
-        }
-        // Since name may only contain ascii characters, for valid names
-        // name.length() returns the number of bytes when UTF-8 encoded.
-        if (name.length() > MAX_VALUE_LENGTH) {
-            throw new IllegalArgumentException(
-                    "name exceeds allowable length: " + name);
-        }
-        for (int i = 0; i < name.length(); i ++) {
-            char c = name.charAt(i);
-            if (c == 0) {
-                throw new IllegalArgumentException(
-                        "name contains null character: " + name);
-            }
-            if (c > 127) {
-                throw new IllegalArgumentException(
-                        "name contains non-ascii character: " + name);
-            }
-        }
-    }
-
-    /**
-     * Validate a HTTP2 header value. Does not validate max length.
-     */
-    private static void validateHeaderValue(String value) {
-        if (value == null) {
-            throw new NullPointerException("value");
-        }
-        for (int i = 0; i < value.length(); i ++) {
-            char c = value.charAt(i);
-            if (c == 0) {
-                throw new IllegalArgumentException(
-                        "value contains null character: " + value);
-            }
-        }
-    }
-
     private final class HeaderIterator implements Iterator<Map.Entry<String, String>> {
 
         private HeaderEntry current = head;

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/Http2Headers.java

@@ -98,12 +98,12 @@ public abstract class Http2Headers implements Iterable<Entry<String, String>> {
 
         private final String value;
 
-        private HttpName(String value) {
+        HttpName(String value) {
             this.value = value;
         }
 
         public String value() {
-            return this.value;
+            return value;
         }
     }
 

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/connection/DefaultInboundFlowController.java

@@ -37,6 +37,9 @@ public class DefaultInboundFlowController implements InboundFlowController {
     private final Map<Integer, StreamWindow> streamWindows = new HashMap<Integer, StreamWindow>();
 
     public DefaultInboundFlowController(Http2Connection connection) {
+        if (connection == null) {
+            throw new NullPointerException("connecton");
+        }
         connection.addListener(new Http2Connection.Listener() {
             @Override
             public void streamCreated(int streamId) {

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/connection/DefaultOutboundFlowController.java

@@ -42,6 +42,9 @@ public class DefaultOutboundFlowController implements OutboundFlowController {
     private int connectionWindowSize = DEFAULT_FLOW_CONTROL_WINDOW_SIZE;
 
     public DefaultOutboundFlowController(Http2Connection connection) {
+        if (connection == null) {
+            throw new NullPointerException("connection");
+        }
         this.connection = connection;
         connection.addListener(new Http2Connection.Listener() {
             @Override

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/connection/Http2ConnectionHandler.java

@@ -65,6 +65,15 @@ public class Http2ConnectionHandler extends ChannelHandlerAdapter {
 
     public Http2ConnectionHandler(final Http2Connection connection,
                                   final InboundFlowController inboundFlow, final OutboundFlowController outboundFlow) {
+        if (connection == null) {
+            throw new NullPointerException("connection");
+        }
+        if (inboundFlow == null) {
+            throw new NullPointerException("inboundFlow");
+        }
+        if (outboundFlow == null) {
+            throw new NullPointerException("outboundFlow");
+        }
         this.connection = connection;
         this.inboundFlow = inboundFlow;
         this.outboundFlow = outboundFlow;

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/connection/Http2ConnectionUtil.java

@@ -22,6 +22,7 @@ import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.http2.draft10.Http2Exception;
+import io.netty.util.CharsetUtil;
 
 /**
  * Constants and utility method used for encoding/decoding HTTP2 frames.
@@ -51,7 +52,7 @@ public final class Http2ConnectionUtil {
         ByteBuf debugData = Unpooled.EMPTY_BUFFER;
         if (cause != null) {
             // Create the debug message.
-            byte[] msg = cause.getMessage().getBytes();
+            byte[] msg = cause.getMessage().getBytes(CharsetUtil.UTF_8);
             debugData = ctx.alloc().buffer(msg.length);
             debugData.writeBytes(msg);
         }

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/decoder/AbstractHttp2FrameUnmarshaller.java

@@ -30,7 +30,7 @@ public abstract class AbstractHttp2FrameUnmarshaller implements Http2FrameUnmars
     @Override
     public final Http2FrameUnmarshaller unmarshall(Http2FrameHeader header) throws Http2Exception {
         if (header == null) {
-            throw new IllegalArgumentException("header must be non-null.");
+            throw new NullPointerException("header");
         }
 
         validate(header);

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/decoder/Http2FrameDecoder.java

@@ -54,6 +54,9 @@ public class Http2FrameDecoder extends ByteToMessageDecoder {
     }
 
     public Http2FrameDecoder(Http2FrameUnmarshaller frameUnmarshaller) {
+        if (frameUnmarshaller == null) {
+            throw new NullPointerException("frameUnmarshaller");
+        }
         this.frameUnmarshaller = frameUnmarshaller;
         state = State.FRAME_HEADER;
     }

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/decoder/Http2HeadersFrameUnmarshaller.java

@@ -40,7 +40,7 @@ public class Http2HeadersFrameUnmarshaller extends AbstractHeadersUnmarshaller {
 
     public Http2HeadersFrameUnmarshaller(Http2HeadersDecoder headersDecoder) {
         if (headersDecoder == null) {
-            throw new IllegalArgumentException("headersDecoder must not be null.");
+            throw new NullPointerException("headersDecoder");
         }
         this.headersDecoder = headersDecoder;
     }

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/decoder/Http2PushPromiseFrameUnmarshaller.java

@@ -39,7 +39,7 @@ public class Http2PushPromiseFrameUnmarshaller extends AbstractHeadersUnmarshall
 
     public Http2PushPromiseFrameUnmarshaller(Http2HeadersDecoder headersDecoder) {
         if (headersDecoder == null) {
-            throw new IllegalArgumentException("headersDecoder must not be null.");
+            throw new NullPointerException("headersDecoder");
         }
         this.headersDecoder = headersDecoder;
     }

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/encoder/AbstractHttp2FrameMarshaller.java

@@ -32,7 +32,7 @@ public abstract class AbstractHttp2FrameMarshaller<T extends Http2Frame> impleme
 
     protected AbstractHttp2FrameMarshaller(Class<T> frameType) {
         if (frameType == null) {
-            throw new IllegalArgumentException("frameType must be non-null.");
+            throw new NullPointerException("frameType");
         }
         this.frameType = frameType;
     }
@@ -41,7 +41,7 @@ public abstract class AbstractHttp2FrameMarshaller<T extends Http2Frame> impleme
     public final void marshall(Http2Frame frame, ByteBuf out, ByteBufAllocator alloc)
             throws Http2Exception {
         if (frame == null) {
-            throw new IllegalArgumentException("frame must be non-null.");
+            throw new NullPointerException("frame");
         }
 
         if (!frameType.isAssignableFrom(frame.getClass())) {

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/encoder/Http2FrameEncoder.java

@@ -36,6 +36,9 @@ public class Http2FrameEncoder extends MessageToByteEncoder<Http2Frame> {
     }
 
     public Http2FrameEncoder(Http2FrameMarshaller frameMarshaller) {
+        if (frameMarshaller == null) {
+            throw new NullPointerException("frameMarshaller");
+        }
         this.frameMarshaller = frameMarshaller;
     }
 

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/encoder/Http2HeadersFrameMarshaller.java

@@ -36,7 +36,7 @@ public class Http2HeadersFrameMarshaller extends AbstractHttp2FrameMarshaller<Ht
     public Http2HeadersFrameMarshaller(Http2HeadersEncoder headersEncoder) {
         super(Http2HeadersFrame.class);
         if (headersEncoder == null) {
-            throw new NullPointerException("headersEncoder must not be null.");
+            throw new NullPointerException("headersEncoder");
         }
         this.headersEncoder = headersEncoder;
     }

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/encoder/Http2PushPromiseFrameMarshaller.java

@@ -34,7 +34,7 @@ public class Http2PushPromiseFrameMarshaller extends
     public Http2PushPromiseFrameMarshaller(Http2HeadersEncoder headersEncoder) {
         super(Http2PushPromiseFrame.class);
         if (headersEncoder == null) {
-            throw new NullPointerException("headersEncoder must not be null.");
+            throw new NullPointerException("headersEncoder");
         }
         this.headersEncoder = headersEncoder;
     }

codec-http2/src/main/java/io/netty/handler/codec/http2/draft10/frame/encoder/Http2StandardFrameMarshaller.java

@@ -79,7 +79,7 @@ public class Http2StandardFrameMarshaller implements Http2FrameMarshaller {
         Http2FrameMarshaller marshaller = null;
 
         if (frame == null) {
-            throw new IllegalArgumentException("frame must be non-null");
+            throw new NullPointerException("frame");
         }
 
         if (frame instanceof Http2DataFrame) {