[2.3.x] Changes for GRIZZLY-1886.

  - Expose server push configuration via Http2Connection and Http2Stream.

Author: rlubke

modules/http2/src/main/java/org/glassfish/grizzly/http2/Http2BaseFilter.java

@@ -645,6 +645,7 @@ void applySettings(final Http2Connection http2Connection,
                 case SettingsFrame.SETTINGS_HEADER_TABLE_SIZE:
                     break;
                 case SettingsFrame.SETTINGS_ENABLE_PUSH:
+                    http2Connection.setPushEnabled(setting.getValue() == 1);
                     break;
                 case SettingsFrame.SETTINGS_MAX_CONCURRENT_STREAMS:
                     http2Connection.setPeerMaxConcurrentStreams(setting.getValue());

modules/http2/src/main/java/org/glassfish/grizzly/http2/Http2Connection.java

@@ -117,6 +117,7 @@ public class Http2Connection {
 
     private int lastPeerStreamId;
     private int lastLocalStreamId;
+    private boolean pushEnabled = true;
 
     private final ReentrantLock newClientStreamLock = new ReentrantLock();
 
@@ -551,6 +552,23 @@ void setPeerMaxConcurrentStreams(int peerMaxConcurrentStreams) {
         this.peerMaxConcurrentStreams = peerMaxConcurrentStreams;
     }
 
+    /**
+     * @return <code>true</code> if push is enabled for this {@link Http2Connection}, otherwise
+     *  returns <code>false</code>.  Push is enabled by default.
+     */
+    public boolean isPushEnabled() {
+        return pushEnabled;
+    }
+
+    /**
+     * Configure whether or not push is enabled on this {@link Http2Connection}.
+     *
+     * @param pushEnabled flag toggling push support.
+     */
+    public void setPushEnabled(final boolean pushEnabled) {
+        this.pushEnabled = pushEnabled;
+    }
+
 
     public int getNextLocalStreamId() {
         lastLocalStreamId += 2;

modules/http2/src/main/java/org/glassfish/grizzly/http2/Http2Stream.java

@@ -248,24 +248,33 @@ public HttpRequestPacket getRequest() {
     public HttpResponsePacket getResponse() {
         return request.getResponse();
     }
+
+    public boolean isPushEnabled() {
+        return http2Connection.isPushEnabled();
+    }
 
     public PushResource addPushResource(final String url,
             final PushResource pushResource) {
-        
-        if (associatedResourcesToPush == null) {
-            associatedResourcesToPush = new HashMap<>();
+        if (isPushEnabled()) {
+            if (associatedResourcesToPush == null) {
+                associatedResourcesToPush = new HashMap<>();
+            }
+
+            return associatedResourcesToPush.put(url, pushResource);
         }
-        
-        return associatedResourcesToPush.put(url, pushResource);
+        return null;
     }
 
     public PushResource removePushResource(final String url) {
-        
-        if (associatedResourcesToPush == null) {
-            return null;
+
+        if (isPushEnabled()) {
+            if (associatedResourcesToPush == null) {
+                return null;
+            }
+
+            return associatedResourcesToPush.remove(url);
         }
-        
-        return associatedResourcesToPush.remove(url);
+        return null;
     }
 
     public int getId() {