Use @SuppressJava6Requirement for animal sniffer plugin to ensure we always guard correctly (#9655)

Motivation:

We can use the `@SuppressJava6Requirement` annotation to be more precise about when we use Java6+ APIs. This helps us to ensure we always protect these places.

Modifications:

Make use of `@SuppressJava6Requirement` explicit

Result:

Fixes https://github.com/netty/netty/issues/2509.

codec-http/src/main/java/io/netty/handler/codec/spdy/SpdyHeaderBlockZlibEncoder.java

@@ -18,6 +18,8 @@ package io.netty.handler.codec.spdy;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.buffer.Unpooled;
+import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 
 import java.util.zip.Deflater;
 
@@ -70,11 +72,17 @@ class SpdyHeaderBlockZlibEncoder extends SpdyHeaderBlockRawEncoder {
         }
     }
 
+    @SuppressJava6Requirement(reason = "Guarded by java version check")
     private boolean compressInto(ByteBuf compressed) {
         byte[] out = compressed.array();
         int off = compressed.arrayOffset() + compressed.writerIndex();
         int toWrite = compressed.writableBytes();
-        int numBytes = compressor.deflate(out, off, toWrite, Deflater.SYNC_FLUSH);
+        final int numBytes;
+        if (PlatformDependent.javaVersion() >= 7) {
+            numBytes = compressor.deflate(out, off, toWrite, Deflater.SYNC_FLUSH);
+        } else {
+            numBytes = compressor.deflate(out, off, toWrite);
+        }
         compressed.writerIndex(compressed.writerIndex() + numBytes);
         return numBytes == toWrite;
     }

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

@@ -22,6 +22,8 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPromise;
 import io.netty.channel.ChannelPromiseNotifier;
 import io.netty.util.concurrent.EventExecutor;
+import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 
 import java.util.concurrent.TimeUnit;
 import java.util.zip.CRC32;
@@ -320,7 +322,11 @@ public class JdkZlibEncoder extends ZlibEncoder {
         return ctx.writeAndFlush(footer, promise);
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     private void deflate(ByteBuf out) {
+        if (PlatformDependent.javaVersion() < 7) {
+            deflateJdk6(out);
+        }
         int numBytes;
         do {
             int writerIndex = out.writerIndex();
@@ -330,6 +336,16 @@ public class JdkZlibEncoder extends ZlibEncoder {
         } while (numBytes > 0);
     }
 
+    private void deflateJdk6(ByteBuf out) {
+        int numBytes;
+        do {
+            int writerIndex = out.writerIndex();
+            numBytes = deflater.deflate(
+                    out.array(), out.arrayOffset() + writerIndex, out.writableBytes());
+            out.writerIndex(writerIndex + numBytes);
+        } while (numBytes > 0);
+    }
+
     @Override
     public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
         this.ctx = ctx;

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

@@ -17,6 +17,7 @@ package io.netty.util.internal;
 
 import java.util.concurrent.atomic.LongAdder;
 
+@SuppressJava6Requirement(reason = "Usage guarded by java version check")
 final class LongAdderCounter extends LongAdder implements LongCounter {
 
     @Override

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

@@ -482,6 +482,7 @@ public final class NativeLibraryLoader {
 
     private static final class NoexecVolumeDetector {
 
+        @SuppressJava6Requirement(reason = "Usage guarded by java version check")
         private static boolean canExecuteExecutable(File file) throws IOException {
             if (PlatformDependent.javaVersion() < 7) {
                 // Pre-JDK7, the Java API did not directly support POSIX permissions; instead of implementing a custom

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

@@ -132,6 +132,7 @@ public final class PlatformDependent {
         if (javaVersion() >= 7) {
             RANDOM_PROVIDER = new ThreadLocalRandomProvider() {
                 @Override
+                @SuppressJava6Requirement(reason = "Usage guarded by java version check")
                 public Random current() {
                     return java.util.concurrent.ThreadLocalRandom.current();
                 }
@@ -964,6 +965,7 @@ public final class PlatformDependent {
     /**
      * Returns a new concurrent {@link Deque}.
      */
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     public static <C> Deque<C> newConcurrentDeque() {
         if (javaVersion() < 7) {
             return new LinkedBlockingDeque<C>();

common/src/main/java/io/netty/util/internal/PlatformDependent0.java

@@ -33,6 +33,7 @@ import static io.netty.util.internal.ObjectUtil.checkNotNull;
 /**
  * The {@link PlatformDependent} operations which requires access to {@code sun.misc.*}.
  */
+@SuppressJava6Requirement(reason = "Unsafe access is guarded")
 final class PlatformDependent0 {
 
     private static final InternalLogger logger = InternalLoggerFactory.getInstance(PlatformDependent0.class);

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

@@ -88,6 +88,7 @@ public final class SocketUtils {
         }
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     public static void bind(final SocketChannel socketChannel, final SocketAddress address) throws IOException {
         try {
             AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() {
@@ -115,6 +116,7 @@ public final class SocketUtils {
         }
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     public static void bind(final DatagramChannel networkChannel, final SocketAddress address) throws IOException {
         try {
             AccessController.doPrivileged(new PrivilegedExceptionAction<Void>() {
@@ -182,6 +184,7 @@ public final class SocketUtils {
         });
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     public static InetAddress loopbackAddress() {
         return AccessController.doPrivileged(new PrivilegedAction<InetAddress>() {
             @Override

common/src/main/java/io/netty/util/internal/SuppressJava6Requirement.java

@@ -25,7 +25,7 @@ import java.lang.annotation.Target;
  * Annotation to suppress the Java 6 source code requirement checks for a method.
  */
 @Retention(RetentionPolicy.CLASS)
-@Target({ ElementType.METHOD, ElementType.CONSTRUCTOR })
+@Target({ ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.TYPE })
 public @interface SuppressJava6Requirement {
 
     String reason();

handler/src/main/java/io/netty/handler/ssl/ExtendedOpenSslSession.java

@@ -15,6 +15,8 @@
  */
 package io.netty.handler.ssl;
 
+import io.netty.util.internal.SuppressJava6Requirement;
+
 import javax.net.ssl.ExtendedSSLSession;
 import javax.net.ssl.SSLException;
 import javax.net.ssl.SSLPeerUnverifiedException;
@@ -29,6 +31,7 @@ import java.util.List;
  * Delegates all operations to a wrapped {@link OpenSslSession} except the methods defined by {@link ExtendedSSLSession}
  * itself.
  */
+@SuppressJava6Requirement(reason = "Usage guarded by java version check")
 abstract class ExtendedOpenSslSession extends ExtendedSSLSession implements OpenSslSession {
 
     // TODO: use OpenSSL API to actually fetch the real data but for now just do what Conscrypt does:

handler/src/main/java/io/netty/handler/ssl/Java7SslParametersUtils.java

@@ -15,6 +15,8 @@
  */
 package io.netty.handler.ssl;
 
+import io.netty.util.internal.SuppressJava6Requirement;
+
 import javax.net.ssl.SSLParameters;
 import java.security.AlgorithmConstraints;
 
@@ -29,6 +31,7 @@ final class Java7SslParametersUtils {
      * {@link AlgorithmConstraints} in the code. This helps us to not get into trouble when using it in java
      * version < 7 and especially when using on android.
      */
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     static void setAlgorithmConstraints(SSLParameters sslParameters, Object algorithmConstraints) {
         sslParameters.setAlgorithmConstraints((AlgorithmConstraints) algorithmConstraints);
     }

handler/src/main/java/io/netty/handler/ssl/Java8SslUtils.java

@@ -15,6 +15,8 @@
  */
 package io.netty.handler.ssl;
 
+import io.netty.util.internal.SuppressJava6Requirement;
+
 import javax.net.ssl.SNIHostName;
 import javax.net.ssl.SNIMatcher;
 import javax.net.ssl.SNIServerName;
@@ -25,6 +27,7 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 
+@SuppressJava6Requirement(reason = "Usage guarded by java version check")
 final class Java8SslUtils {
 
     private Java8SslUtils() { }

handler/src/main/java/io/netty/handler/ssl/Java9SslEngine.java

@@ -16,6 +16,7 @@
 package io.netty.handler.ssl;
 
 import io.netty.util.internal.StringUtil;
+import io.netty.util.internal.SuppressJava6Requirement;
 
 import javax.net.ssl.SSLEngine;
 import javax.net.ssl.SSLEngineResult;
@@ -30,6 +31,7 @@ import static io.netty.handler.ssl.SslUtils.toSSLHandshakeException;
 import static io.netty.handler.ssl.JdkApplicationProtocolNegotiator.ProtocolSelectionListener;
 import static io.netty.handler.ssl.JdkApplicationProtocolNegotiator.ProtocolSelector;
 
+@SuppressJava6Requirement(reason = "Usage guarded by java version check")
 final class Java9SslEngine extends JdkSslEngine {
     private final ProtocolSelectionListener selectionListener;
     private final AlpnSelector alpnSelector;

handler/src/main/java/io/netty/handler/ssl/Java9SslUtils.java

@@ -27,9 +27,11 @@ import java.util.function.BiFunction;
 
 import io.netty.util.internal.EmptyArrays;
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 
+@SuppressJava6Requirement(reason = "Usage guarded by java version check")
 final class Java9SslUtils {
     private static final InternalLogger logger = InternalLoggerFactory.getInstance(Java9SslUtils.class);
     private static final Method SET_APPLICATION_PROTOCOLS;

handler/src/main/java/io/netty/handler/ssl/JdkSslEngine.java

@@ -15,6 +15,8 @@
  */
 package io.netty.handler.ssl;
 
+import io.netty.util.internal.SuppressJava6Requirement;
+
 import java.nio.ByteBuffer;
 
 import javax.net.ssl.SSLEngine;
@@ -145,6 +147,7 @@ class JdkSslEngine extends SSLEngine implements ApplicationProtocolAccessor {
         engine.setEnabledProtocols(strings);
     }
 
+    @SuppressJava6Requirement(reason = "Can only be called when running on JDK7+")
     @Override
     public SSLSession getHandshakeSession() {
         return engine.getHandshakeSession();

handler/src/main/java/io/netty/handler/ssl/OpenSslTlsv13X509ExtendedTrustManager.java

@@ -16,6 +16,7 @@
 package io.netty.handler.ssl;
 
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 
 import javax.net.ssl.SSLEngine;
 import javax.net.ssl.SSLPeerUnverifiedException;
@@ -35,6 +36,7 @@ import java.util.List;
  * default {@link X509ExtendedTrustManager} implementations provided by the JDK that can not handle a protocol version
  * of {@code TLSv1.3}.
  */
+@SuppressJava6Requirement(reason = "Usage guarded by java version check")
 final class OpenSslTlsv13X509ExtendedTrustManager extends X509ExtendedTrustManager {
 
     private final X509ExtendedTrustManager tm;

handler/src/main/java/io/netty/handler/ssl/OpenSslX509Certificate.java

@@ -15,6 +15,8 @@
  */
 package io.netty.handler.ssl;
 
+import io.netty.util.internal.SuppressJava6Requirement;
+
 import javax.security.auth.x500.X500Principal;
 import java.io.ByteArrayInputStream;
 import java.math.BigInteger;
@@ -81,7 +83,7 @@ final class OpenSslX509Certificate extends X509Certificate {
     }
 
     // No @Override annotation as it was only introduced in Java8.
-    @Override
+    @SuppressJava6Requirement(reason = "Can only be called from Java8 as class is package-private")
     public void verify(PublicKey key, Provider sigProvider)
             throws CertificateException, NoSuchAlgorithmException, InvalidKeyException, SignatureException {
         unwrap().verify(key, sigProvider);

handler/src/main/java/io/netty/handler/ssl/OpenSslX509TrustManagerWrapper.java

@@ -17,6 +17,7 @@ package io.netty.handler.ssl;
 
 import io.netty.util.internal.EmptyArrays;
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 
@@ -39,6 +40,7 @@ import java.security.cert.X509Certificate;
  * This is really a "hack" until there is an official API as requested on the in
  * <a href="https://bugs.openjdk.java.net/projects/JDK/issues/JDK-8210843">JDK-8210843</a>.
  */
+@SuppressJava6Requirement(reason = "Usage guarded by java version check")
 final class OpenSslX509TrustManagerWrapper {
     private static final InternalLogger LOGGER = InternalLoggerFactory
             .getInstance(OpenSslX509TrustManagerWrapper.class);
@@ -163,6 +165,7 @@ final class OpenSslX509TrustManagerWrapper {
             this.tmOffset = tmOffset;
         }
 
+        @SuppressJava6Requirement(reason = "Usage guarded by java version check")
         @Override
         public X509TrustManager wrapIfNeeded(X509TrustManager manager) {
             if (!(manager instanceof X509ExtendedTrustManager)) {

handler/src/main/java/io/netty/handler/ssl/ReferenceCountedOpenSslClientContext.java

@@ -16,6 +16,7 @@
 package io.netty.handler.ssl;
 
 import io.netty.internal.tcnative.CertificateCallback;
+import io.netty.util.internal.SuppressJava6Requirement;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 import io.netty.internal.tcnative.SSL;
@@ -155,13 +156,7 @@ public final class ReferenceCountedOpenSslClientContext extends ReferenceCounted
                 //
                 //            See https://github.com/netty/netty/issues/5372
 
-                // Use this to prevent an error when running on java < 7
+                setVerifyCallback(ctx, engineMap, manager);
-                if (useExtendedTrustManager(manager)) {
-                    SSLContext.setCertVerifyCallback(ctx,
-                            new ExtendedTrustManagerVerifyCallback(engineMap, (X509ExtendedTrustManager) manager));
-                } else {
-                    SSLContext.setCertVerifyCallback(ctx, new TrustManagerVerifyCallback(engineMap, manager));
-                }
             } catch (Exception e) {
                 if (keyMaterialProvider != null) {
                     keyMaterialProvider.destroy();
@@ -178,6 +173,17 @@ public final class ReferenceCountedOpenSslClientContext extends ReferenceCounted
         }
     }
 
+    @SuppressJava6Requirement(reason = "Guarded by java version check")
+    private static void setVerifyCallback(long ctx, OpenSslEngineMap engineMap, X509TrustManager manager) {
+        // Use this to prevent an error when running on java < 7
+        if (useExtendedTrustManager(manager)) {
+            SSLContext.setCertVerifyCallback(ctx,
+                    new ExtendedTrustManagerVerifyCallback(engineMap, (X509ExtendedTrustManager) manager));
+        } else {
+            SSLContext.setCertVerifyCallback(ctx, new TrustManagerVerifyCallback(engineMap, manager));
+        }
+    }
+
     // No cache is currently supported for client side mode.
     static final class OpenSslClientSessionContext extends OpenSslSessionContext {
         OpenSslClientSessionContext(ReferenceCountedOpenSslContext context, OpenSslKeyMaterialProvider provider) {
@@ -234,6 +240,7 @@ public final class ReferenceCountedOpenSslClientContext extends ReferenceCounted
         }
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     private static final class ExtendedTrustManagerVerifyCallback extends AbstractCertificateVerifier {
         private final X509ExtendedTrustManager manager;
 

handler/src/main/java/io/netty/handler/ssl/ReferenceCountedOpenSslContext.java

@@ -29,6 +29,7 @@ import io.netty.util.ResourceLeakTracker;
 import io.netty.util.internal.ObjectUtil;
 import io.netty.util.internal.PlatformDependent;
 import io.netty.util.internal.StringUtil;
+import io.netty.util.internal.SuppressJava6Requirement;
 import io.netty.util.internal.SystemPropertyUtil;
 import io.netty.util.internal.UnstableApi;
 import io.netty.util.internal.logging.InternalLogger;
@@ -637,6 +638,7 @@ public abstract class ReferenceCountedOpenSslContext extends SslContext implemen
         }
     }
 
+    @SuppressJava6Requirement(reason = "Guarded by java version check")
     static boolean useExtendedTrustManager(X509TrustManager trustManager) {
         return PlatformDependent.javaVersion() >= 7 && trustManager instanceof X509ExtendedTrustManager;
     }
@@ -715,6 +717,16 @@ public abstract class ReferenceCountedOpenSslContext extends SslContext implemen
                     return CertificateVerifier.X509_V_ERR_CERT_NOT_YET_VALID;
                 }
                 if (PlatformDependent.javaVersion() >= 7) {
+                    return translateToError(cause);
+                }
+
+                // Could not detect a specific error code to use, so fallback to a default code.
+                return CertificateVerifier.X509_V_ERR_UNSPECIFIED;
+            }
+        }
+
+        @SuppressJava6Requirement(reason = "Usage guarded by java version check")
+        private static int translateToError(Throwable cause) {
             if (cause instanceof CertificateRevokedException) {
                 return CertificateVerifier.X509_V_ERR_CERT_REVOKED;
             }
@@ -739,12 +751,8 @@ public abstract class ReferenceCountedOpenSslContext extends SslContext implemen
                 }
                 wrapped = wrapped.getCause();
             }
-                }
-
-                // Could not detect a specific error code to use, so fallback to a default code.
             return CertificateVerifier.X509_V_ERR_UNSPECIFIED;
         }
-        }
 
         abstract void verify(ReferenceCountedOpenSslEngine engine, X509Certificate[] peerCerts,
                              String auth) throws Exception;

handler/src/main/java/io/netty/handler/ssl/ReferenceCountedOpenSslEngine.java

@@ -28,6 +28,7 @@ import io.netty.util.ResourceLeakTracker;
 import io.netty.util.internal.EmptyArrays;
 import io.netty.util.internal.PlatformDependent;
 import io.netty.util.internal.StringUtil;
+import io.netty.util.internal.SuppressJava6Requirement;
 import io.netty.util.internal.UnstableApi;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
@@ -1952,6 +1953,7 @@ public class ReferenceCountedOpenSslEngine extends SSLEngine implements Referenc
         return false;
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     @Override
     public final synchronized SSLParameters getSSLParameters() {
         SSLParameters sslParameters = super.getSSLParameters();
@@ -1975,6 +1977,7 @@ public class ReferenceCountedOpenSslEngine extends SSLEngine implements Referenc
         return sslParameters;
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     @Override
     public final synchronized void setSSLParameters(SSLParameters sslParameters) {
         int version = PlatformDependent.javaVersion();

handler/src/main/java/io/netty/handler/ssl/ReferenceCountedOpenSslServerContext.java

@@ -22,6 +22,7 @@ import io.netty.internal.tcnative.SSLContext;
 import io.netty.internal.tcnative.SniHostNameMatcher;
 import io.netty.util.CharsetUtil;
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 
@@ -147,13 +148,7 @@ public final class ReferenceCountedOpenSslServerContext extends ReferenceCounted
                 //
                 //            See https://github.com/netty/netty/issues/5372
 
-                // Use this to prevent an error when running on java < 7
+                setVerifyCallback(ctx, engineMap, manager);
-                if (useExtendedTrustManager(manager)) {
-                    SSLContext.setCertVerifyCallback(ctx, new ExtendedTrustManagerVerifyCallback(
-                            engineMap, (X509ExtendedTrustManager) manager));
-                } else {
-                    SSLContext.setCertVerifyCallback(ctx, new TrustManagerVerifyCallback(engineMap, manager));
-                }
 
                 X509Certificate[] issuers = manager.getAcceptedIssuers();
                 if (issuers != null && issuers.length > 0) {
@@ -194,6 +189,17 @@ public final class ReferenceCountedOpenSslServerContext extends ReferenceCounted
         }
     }
 
+    @SuppressJava6Requirement(reason = "Guarded by java version check")
+    private static void setVerifyCallback(long ctx, OpenSslEngineMap engineMap, X509TrustManager manager) {
+        // Use this to prevent an error when running on java < 7
+        if (useExtendedTrustManager(manager)) {
+            SSLContext.setCertVerifyCallback(ctx, new ExtendedTrustManagerVerifyCallback(
+                    engineMap, (X509ExtendedTrustManager) manager));
+        } else {
+            SSLContext.setCertVerifyCallback(ctx, new TrustManagerVerifyCallback(engineMap, manager));
+        }
+    }
+
     private static final class OpenSslServerCertificateCallback implements CertificateCallback {
         private final OpenSslEngineMap engineMap;
         private final OpenSslKeyMaterialManager keyManagerHolder;
@@ -236,6 +242,7 @@ public final class ReferenceCountedOpenSslServerContext extends ReferenceCounted
         }
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     private static final class ExtendedTrustManagerVerifyCallback extends AbstractCertificateVerifier {
         private final X509ExtendedTrustManager manager;
 

handler/src/main/java/io/netty/handler/ssl/util/OpenJdkSelfSignedCertGenerator.java

@@ -16,6 +16,7 @@
 
 package io.netty.handler.ssl.util;
 
+import io.netty.util.internal.SuppressJava6Requirement;
 import sun.security.x509.AlgorithmId;
 import sun.security.x509.CertificateAlgorithmId;
 import sun.security.x509.CertificateIssuerName;
@@ -42,6 +43,7 @@ import static io.netty.handler.ssl.util.SelfSignedCertificate.*;
  */
 final class OpenJdkSelfSignedCertGenerator {
 
+    @SuppressJava6Requirement(reason = "Usage guarded by dependency check")
     static String[] generate(String fqdn, KeyPair keypair, SecureRandom random, Date notBefore, Date notAfter)
             throws Exception {
         PrivateKey key = keypair.getPrivate();

handler/src/main/java/io/netty/handler/ssl/util/SimpleTrustManagerFactory.java

@@ -18,6 +18,7 @@ package io.netty.handler.ssl.util;
 
 import io.netty.util.concurrent.FastThreadLocal;
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 
 import javax.net.ssl.ManagerFactoryParameters;
 import javax.net.ssl.TrustManager;
@@ -136,6 +137,15 @@ public abstract class SimpleTrustManagerFactory extends TrustManagerFactory {
             if (trustManagers == null) {
                 trustManagers = parent.engineGetTrustManagers();
                 if (PlatformDependent.javaVersion() >= 7) {
+                    wrapIfNeeded(trustManagers);
+                }
+                this.trustManagers = trustManagers;
+            }
+            return trustManagers.clone();
+        }
+
+        @SuppressJava6Requirement(reason = "Usage guarded by java version check")
+        private static void wrapIfNeeded(TrustManager[] trustManagers) {
             for (int i = 0; i < trustManagers.length; i++) {
                 final TrustManager tm = trustManagers[i];
                 if (tm instanceof X509TrustManager && !(tm instanceof X509ExtendedTrustManager)) {
@@ -143,9 +153,5 @@ public abstract class SimpleTrustManagerFactory extends TrustManagerFactory {
                 }
             }
         }
-                this.trustManagers = trustManagers;
-            }
-            return trustManagers.clone();
-        }
     }
 }

handler/src/main/java/io/netty/handler/ssl/util/X509TrustManagerWrapper.java

@@ -15,6 +15,8 @@
  */
 package io.netty.handler.ssl.util;
 
+import io.netty.util.internal.SuppressJava6Requirement;
+
 import javax.net.ssl.SSLEngine;
 import javax.net.ssl.X509ExtendedTrustManager;
 import javax.net.ssl.X509TrustManager;
@@ -24,6 +26,7 @@ import java.security.cert.X509Certificate;
 
 import static io.netty.util.internal.ObjectUtil.*;
 
+@SuppressJava6Requirement(reason = "Usage guarded by java version check")
 final class X509TrustManagerWrapper extends X509ExtendedTrustManager {
 
     private final X509TrustManager delegate;

pom.xml

@@ -819,78 +819,7 @@
             <version>1.1</version>
           </signature>
           <ignores>
-            <ignore>sun.misc.Unsafe</ignore>
-            <ignore>sun.misc.Cleaner</ignore>
-            <ignore>sun.nio.ch.DirectBuffer</ignore>
-
-            <ignore>java.util.zip.Deflater</ignore>
-
-            <!-- Used for NIO -->
-            <ignore>java.nio.channels.DatagramChannel</ignore>
-            <ignore>java.nio.channels.MembershipKey</ignore>
-            <ignore>java.nio.channels.ServerSocketChannel</ignore>
-            <ignore>java.nio.channels.SocketChannel</ignore>
-            <ignore>java.net.StandardProtocolFamily</ignore>
-            <ignore>java.nio.channels.spi.SelectorProvider</ignore>
-            <ignore>java.net.SocketOption</ignore>
-            <ignore>java.net.StandardSocketOptions</ignore>
-            <ignore>java.nio.channels.NetworkChannel</ignore>
-
-            <!-- Self-signed certificate generation -->
-            <ignore>sun.security.x509.AlgorithmId</ignore>
-            <ignore>sun.security.x509.CertificateAlgorithmId</ignore>
-            <ignore>sun.security.x509.CertificateIssuerName</ignore>
-            <ignore>sun.security.x509.CertificateSerialNumber</ignore>
-            <ignore>sun.security.x509.CertificateSubjectName</ignore>
-            <ignore>sun.security.x509.CertificateValidity</ignore>
-            <ignore>sun.security.x509.CertificateVersion</ignore>
-            <ignore>sun.security.x509.CertificateX509Key</ignore>
-            <ignore>sun.security.x509.X500Name</ignore>
-            <ignore>sun.security.x509.X509CertInfo</ignore>
-            <ignore>sun.security.x509.X509CertImpl</ignore>
-
-            <!-- SSLSession implementation -->
-            <ignore>javax.net.ssl.SSLEngine</ignore>
-            <ignore>javax.net.ssl.ExtendedSSLSession</ignore>
-            <ignore>javax.net.ssl.X509ExtendedTrustManager</ignore>
-            <ignore>javax.net.ssl.SSLParameters</ignore>
-            <ignore>javax.net.ssl.SNIServerName</ignore>
-            <ignore>javax.net.ssl.SNIHostName</ignore>
-            <ignore>javax.net.ssl.SNIMatcher</ignore>
-            <ignore>java.security.AlgorithmConstraints</ignore>
-            <ignore>java.security.cert.CertificateRevokedException</ignore>
-            <ignore>java.security.cert.CertPathValidatorException</ignore>
-            <ignore>java.security.cert.CertPathValidatorException$Reason</ignore>
-            <ignore>java.security.cert.CertPathValidatorException$BasicReason</ignore>
-
-            <ignore>java.util.concurrent.ConcurrentLinkedDeque</ignore>
-            <ignore>java.util.concurrent.ThreadLocalRandom</ignore>
-
-            <!-- Compression -->
-            <ignore>java.util.zip.CRC32</ignore>
-            <ignore>java.util.zip.Adler32</ignore>
-
-            <!-- NioDatagramChannel implementation -->
-            <ignore>java.net.ProtocolFamily</ignore>
-
-            <!-- JDK 9 -->
             <ignore>java.nio.ByteBuffer</ignore>
-            <ignore>java.nio.CharBuffer</ignore>
-
-            <!-- JDK 8 -->
-            <ignore>java.util.concurrent.atomic.LongAdder</ignore>
-            <ignore>java.util.function.BiFunction</ignore>
-            <ignore>java.security.cert.X509Certificate</ignore>
-
-            <!-- Resolver -->
-            <ignore>java.net.InetAddress</ignore>
-
-            <!-- NoexecVolumeDetector -->
-            <ignore>java.nio.file.attribute.PosixFilePermission</ignore>
-            <ignore>java.nio.file.Files</ignore>
-            <ignore>java.nio.file.LinkOption</ignore>
-            <ignore>java.nio.file.Path</ignore>
-            <ignore>java.io.File</ignore>
           </ignores>
           <annotations>
             <annotation>io.netty.util.internal.SuppressJava6Requirement</annotation>

testsuite/src/main/java/io/netty/testsuite/transport/socket/DatagramUnicastIPv6Test.java

@@ -16,6 +16,8 @@
 package io.netty.testsuite.transport.socket;
 
 import io.netty.channel.socket.InternetProtocolFamily;
+import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 import org.junit.Assume;
 import org.junit.BeforeClass;
 
@@ -26,9 +28,13 @@ import java.nio.channels.spi.SelectorProvider;
 
 public class DatagramUnicastIPv6Test extends DatagramUnicastTest {
 
+    @SuppressJava6Requirement(reason = "Guarded by java version check")
     @BeforeClass
     public static void assumeIpv6Supported() {
         try {
+            if (PlatformDependent.javaVersion() < 7) {
+                throw new UnsupportedOperationException();
+            }
             Channel channel = SelectorProvider.provider().openDatagramChannel(StandardProtocolFamily.INET6);
             channel.close();
         } catch (UnsupportedOperationException e) {

transport/src/main/java/io/netty/channel/socket/nio/NioChannelOption.java

@@ -17,6 +17,7 @@ package io.netty.channel.socket.nio;
 
 import io.netty.channel.ChannelException;
 import io.netty.channel.ChannelOption;
+import io.netty.util.internal.SuppressJava6Requirement;
 
 import java.io.IOException;
 import java.nio.channels.Channel;
@@ -29,6 +30,7 @@ import java.util.Set;
  * Provides {@link ChannelOption} over a given {@link java.net.SocketOption} which is then passed through the underlying
  * {@link java.nio.channels.NetworkChannel}.
  */
+@SuppressJava6Requirement(reason = "Usage explicit by the user")
 public final class NioChannelOption<T> extends ChannelOption<T> {
 
     private final java.net.SocketOption<T> option;
@@ -53,6 +55,7 @@ public final class NioChannelOption<T> extends ChannelOption<T> {
     // See https://github.com/netty/netty/issues/8166
 
     // Internal helper methods to remove code duplication between Nio*Channel implementations.
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     static <T> boolean setOption(Channel jdkChannel, NioChannelOption<T> option, T value) {
         java.nio.channels.NetworkChannel channel = (java.nio.channels.NetworkChannel) jdkChannel;
         if (!channel.supportedOptions().contains(option.option)) {
@@ -71,6 +74,7 @@ public final class NioChannelOption<T> extends ChannelOption<T> {
         }
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     static <T> T getOption(Channel jdkChannel, NioChannelOption<T> option) {
         java.nio.channels.NetworkChannel channel = (java.nio.channels.NetworkChannel) jdkChannel;
 
@@ -89,6 +93,7 @@ public final class NioChannelOption<T> extends ChannelOption<T> {
         }
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     @SuppressWarnings("unchecked")
     static ChannelOption[] getOptions(Channel jdkChannel) {
         java.nio.channels.NetworkChannel channel = (java.nio.channels.NetworkChannel) jdkChannel;

transport/src/main/java/io/netty/channel/socket/nio/NioDatagramChannel.java

@@ -33,6 +33,7 @@ import io.netty.channel.socket.InternetProtocolFamily;
 import io.netty.util.internal.SocketUtils;
 import io.netty.util.internal.PlatformDependent;
 import io.netty.util.internal.StringUtil;
+import io.netty.util.internal.SuppressJava6Requirement;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -88,6 +89,7 @@ public final class NioDatagramChannel
         }
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     private static DatagramChannel newSocket(SelectorProvider provider, InternetProtocolFamily ipFamily) {
         if (ipFamily == null) {
             return newSocket(provider);
@@ -394,6 +396,7 @@ public final class NioDatagramChannel
         return joinGroup(multicastAddress, networkInterface, source, newPromise());
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     @Override
     public ChannelFuture joinGroup(
             InetAddress multicastAddress, NetworkInterface networkInterface,
@@ -474,6 +477,7 @@ public final class NioDatagramChannel
         return leaveGroup(multicastAddress, networkInterface, source, newPromise());
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     @Override
     public ChannelFuture leaveGroup(
             InetAddress multicastAddress, NetworkInterface networkInterface, InetAddress source,
@@ -527,6 +531,7 @@ public final class NioDatagramChannel
     /**
      * Block the given sourceToBlock address for the given multicastAddress on the given networkInterface
      */
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     @Override
     public ChannelFuture block(
             InetAddress multicastAddress, NetworkInterface networkInterface,

transport/src/main/java/io/netty/channel/socket/nio/NioServerSocketChannel.java

@@ -24,6 +24,7 @@ import io.netty.channel.nio.AbstractNioMessageChannel;
 import io.netty.channel.socket.DefaultServerSocketChannelConfig;
 import io.netty.channel.socket.ServerSocketChannelConfig;
 import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SuppressJava6Requirement;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 
@@ -126,6 +127,7 @@ public class NioServerSocketChannel extends AbstractNioMessageChannel
         return SocketUtils.localSocketAddress(javaChannel().socket());
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     @Override
     protected void doBind(SocketAddress localAddress) throws Exception {
         if (PlatformDependent.javaVersion() >= 7) {
@@ -220,7 +222,6 @@ public class NioServerSocketChannel extends AbstractNioMessageChannel
             return super.getOption(option);
         }
 
-        @SuppressWarnings("unchecked")
         @Override
         public Map<ChannelOption<?>, Object> getOptions() {
             if (PlatformDependent.javaVersion() >= 7) {

transport/src/main/java/io/netty/channel/socket/nio/NioSocketChannel.java

@@ -33,6 +33,7 @@ import io.netty.channel.socket.SocketChannelConfig;
 import io.netty.util.concurrent.GlobalEventExecutor;
 import io.netty.util.internal.PlatformDependent;
 import io.netty.util.internal.SocketUtils;
+import io.netty.util.internal.SuppressJava6Requirement;
 import io.netty.util.internal.UnstableApi;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
@@ -152,6 +153,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
         return (InetSocketAddress) super.remoteAddress();
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     @UnstableApi
     @Override
     protected final void doShutdownOutput() throws Exception {
@@ -270,6 +272,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
         }
     }
 
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     private void shutdownInput0() throws Exception {
         if (PlatformDependent.javaVersion() >= 7) {
             javaChannel().shutdownInput();
@@ -496,7 +499,6 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
             return super.getOption(option);
         }
 
-        @SuppressWarnings("unchecked")
         @Override
         public Map<ChannelOption<?>, Object> getOptions() {
             if (PlatformDependent.javaVersion() >= 7) {

transport/src/main/java/io/netty/channel/socket/nio/ProtocolFamilyConverter.java

@@ -16,6 +16,7 @@
 package io.netty.channel.socket.nio;
 
 import io.netty.channel.socket.InternetProtocolFamily;
+import io.netty.util.internal.SuppressJava6Requirement;
 
 import java.net.ProtocolFamily;
 import java.net.StandardProtocolFamily;
@@ -32,6 +33,7 @@ final class ProtocolFamilyConverter {
     /**
      * Convert the {@link InternetProtocolFamily}. This MUST only be called on jdk version >= 7.
      */
+    @SuppressJava6Requirement(reason = "Usage guarded by java version check")
     public static ProtocolFamily convert(InternetProtocolFamily family) {
         switch (family) {
         case IPv4: