Move GCP proxy code to the old [] proxy's location

1. Moved code for the GCP proxy to where the [] proxy code used to live.
3. Corrected reference to the GCP proxy location.
4. Misc changes to make ErrorProne and various tools happy.

+diekmann to LGTM terraform whitelist change.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=213630560

java/google/registry/proxy/handler/WhoisServiceHandler.java

@@ -0,0 +1,66 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// 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
+//
+//     http://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 google.registry.proxy.handler;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import google.registry.proxy.metric.FrontendMetrics;
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelFutureListener;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelPromise;
+import io.netty.handler.codec.http.FullHttpRequest;
+import io.netty.handler.codec.http.HttpHeaderNames;
+import io.netty.handler.codec.http.HttpHeaderValues;
+import io.netty.handler.codec.http.HttpResponse;
+import java.util.function.Supplier;
+
+/** Handler that processes WHOIS protocol logic. */
+public final class WhoisServiceHandler extends HttpsRelayServiceHandler {
+
+  public WhoisServiceHandler(
+      String relayHost,
+      String relayPath,
+      Supplier<String> accessTokenSupplier,
+      FrontendMetrics metrics) {
+    super(relayHost, relayPath, accessTokenSupplier, metrics);
+  }
+
+  @Override
+  public void channelActive(ChannelHandlerContext ctx) throws Exception {
+    metrics.registerActiveConnection("whois", "none", ctx.channel());
+    super.channelActive(ctx);
+  }
+
+  @Override
+  protected FullHttpRequest decodeFullHttpRequest(ByteBuf byteBuf) {
+    FullHttpRequest request = super.decodeFullHttpRequest(byteBuf);
+    request
+        .headers()
+        .set(HttpHeaderNames.CONTENT_TYPE, HttpHeaderValues.TEXT_PLAIN)
+        .set(HttpHeaderNames.ACCEPT, HttpHeaderValues.TEXT_PLAIN);
+    return request;
+  }
+
+  @Override
+  public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise)
+      throws Exception {
+    // Close connection after a response is received, per RFC-3912
+    // https://tools.ietf.org/html/rfc3912
+    checkArgument(msg instanceof HttpResponse);
+    promise.addListener(ChannelFutureListener.CLOSE);
+    super.write(ctx, msg, promise);
+  }
+}