netty: Increase HPACK encoder bucket count to 128

Co-Authored-By: Codex <noreply@openai.com>

Author: petedmarsh

netty/src/main/java/io/grpc/netty/NettyClientHandler.java

@@ -175,8 +175,10 @@ static NettyClientHandler newHandler(
     Preconditions.checkArgument(maxHeaderListSize > 0, "maxHeaderListSize must be positive");
     Http2HeadersDecoder headersDecoder = new GrpcHttp2ClientHeadersDecoder(maxHeaderListSize);
     Http2FrameReader frameReader = new DefaultHttp2FrameReader(headersDecoder);
+    // TODO: Add support upstream in Netty for injecting a custom Http2HeadersEncoder subclass
+    // into Http2FrameCodecBuilder before migrating to that API.
     Http2HeadersEncoder encoder = new DefaultHttp2HeadersEncoder(
-        sensitivityDetector(neverIndexedMetadataKeys), false, 16, Integer.MAX_VALUE);
+        sensitivityDetector(neverIndexedMetadataKeys), false, 128, Integer.MAX_VALUE);
     Http2FrameWriter frameWriter = new DefaultHttp2FrameWriter(encoder);
     Http2Connection connection = new DefaultHttp2Connection(false);
     UniformStreamByteDistributor dist = new UniformStreamByteDistributor(connection);

netty/src/main/java/io/grpc/netty/NettyServerHandler.java

@@ -189,7 +189,7 @@ static NettyServerHandler newHandler(
     Http2HeadersEncoder encoder = new DefaultHttp2HeadersEncoder(
         NettyClientHandler.sensitivityDetector(neverIndexedMetadataKeys),
         false,
-        16,
+        128,
         Integer.MAX_VALUE);
     Http2FrameWriter frameWriter =
         new Http2OutboundFrameLogger(new DefaultHttp2FrameWriter(encoder), frameLogger);