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

javatests/google/registry/proxy/handler/EppQuotaHandlerTest.java

@@ -0,0 +1,170 @@
+// 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.truth.Truth.assertThat;
+import static google.registry.proxy.Protocol.PROTOCOL_KEY;
+import static google.registry.proxy.handler.EppServiceHandler.CLIENT_CERTIFICATE_HASH_KEY;
+import static google.registry.testing.JUnitBackports.assertThrows;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.mockito.Mockito.when;
+
+import com.google.common.collect.ImmutableList;
+import google.registry.proxy.Protocol;
+import google.registry.proxy.handler.QuotaHandler.EppQuotaHandler;
+import google.registry.proxy.handler.QuotaHandler.OverQuotaException;
+import google.registry.proxy.metric.FrontendMetrics;
+import google.registry.proxy.quota.QuotaManager;
+import google.registry.proxy.quota.QuotaManager.QuotaRebate;
+import google.registry.proxy.quota.QuotaManager.QuotaRequest;
+import google.registry.proxy.quota.QuotaManager.QuotaResponse;
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelFuture;
+import io.netty.channel.embedded.EmbeddedChannel;
+import org.joda.time.DateTime;
+import org.joda.time.DateTimeZone;
+import org.joda.time.Duration;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link EppQuotaHandler} */
+@RunWith(JUnit4.class)
+public class EppQuotaHandlerTest {
+
+  private final QuotaManager quotaManager = mock(QuotaManager.class);
+  private final FrontendMetrics metrics = mock(FrontendMetrics.class);
+  private final EppQuotaHandler handler = new EppQuotaHandler(quotaManager, metrics);
+  private final EmbeddedChannel channel = new EmbeddedChannel(handler);
+  private final String clientCertHash = "blah/123!";
+  private final DateTime now = DateTime.now(DateTimeZone.UTC);
+  private final Object message = new Object();
+
+  private void setProtocol(Channel channel) {
+    channel
+        .attr(PROTOCOL_KEY)
+        .set(
+            Protocol.frontendBuilder()
+                .name("epp")
+                .port(12345)
+                .handlerProviders(ImmutableList.of())
+                .relayProtocol(
+                    Protocol.backendBuilder()
+                        .name("backend")
+                        .host("host.tld")
+                        .port(1234)
+                        .handlerProviders(ImmutableList.of())
+                        .build())
+                .build());
+  }
+
+  @Before
+  public void setUp() {
+    channel.attr(CLIENT_CERTIFICATE_HASH_KEY).set(clientCertHash);
+    setProtocol(channel);
+  }
+
+  @Test
+  public void testSuccess_quotaGrantedAndReturned() {
+    when(quotaManager.acquireQuota(QuotaRequest.create(clientCertHash)))
+        .thenReturn(QuotaResponse.create(true, clientCertHash, now));
+
+    // First read, acquire quota.
+    assertThat(channel.writeInbound(message)).isTrue();
+    assertThat((Object) channel.readInbound()).isEqualTo(message);
+    assertThat(channel.isActive()).isTrue();
+    verify(quotaManager).acquireQuota(QuotaRequest.create(clientCertHash));
+
+    // Second read, should not acquire quota again.
+    Object newMessage = new Object();
+    assertThat(channel.writeInbound(newMessage)).isTrue();
+    assertThat((Object) channel.readInbound()).isEqualTo(newMessage);
+    verifyNoMoreInteractions(quotaManager);
+
+    // Channel closed, release quota.
+    ChannelFuture unusedFuture = channel.close();
+    verify(quotaManager)
+        .releaseQuota(QuotaRebate.create(QuotaResponse.create(true, clientCertHash, now)));
+    verifyNoMoreInteractions(quotaManager);
+  }
+
+  @Test
+  public void testFailure_quotaNotGranted() {
+    when(quotaManager.acquireQuota(QuotaRequest.create(clientCertHash)))
+        .thenReturn(QuotaResponse.create(false, clientCertHash, now));
+    OverQuotaException e =
+        assertThrows(OverQuotaException.class, () -> channel.writeInbound(message));
+    assertThat(e).hasMessageThat().contains(clientCertHash);
+    verify(metrics).registerQuotaRejection("epp", clientCertHash);
+    verifyNoMoreInteractions(metrics);
+  }
+
+  @Test
+  public void testSuccess_twoChannels_twoUserIds() {
+    // Set up another user.
+    final EppQuotaHandler otherHandler = new EppQuotaHandler(quotaManager, metrics);
+    final EmbeddedChannel otherChannel = new EmbeddedChannel(otherHandler);
+    final String otherClientCertHash = "hola@9x";
+    otherChannel.attr(CLIENT_CERTIFICATE_HASH_KEY).set(otherClientCertHash);
+    setProtocol(otherChannel);
+    final DateTime later = now.plus(Duration.standardSeconds(1));
+
+    when(quotaManager.acquireQuota(QuotaRequest.create(clientCertHash)))
+        .thenReturn(QuotaResponse.create(true, clientCertHash, now));
+    when(quotaManager.acquireQuota(QuotaRequest.create(otherClientCertHash)))
+        .thenReturn(QuotaResponse.create(false, otherClientCertHash, later));
+
+    // Allows the first user.
+    assertThat(channel.writeInbound(message)).isTrue();
+    assertThat((Object) channel.readInbound()).isEqualTo(message);
+    assertThat(channel.isActive()).isTrue();
+
+    // Blocks the second user.
+    OverQuotaException e =
+        assertThrows(OverQuotaException.class, () -> otherChannel.writeInbound(message));
+    assertThat(e).hasMessageThat().contains(otherClientCertHash);
+    verify(metrics).registerQuotaRejection("epp", otherClientCertHash);
+    verifyNoMoreInteractions(metrics);
+  }
+
+  @Test
+  public void testSuccess_twoChannels_sameUserIds() {
+    // Set up another channel for the same user.
+    final EppQuotaHandler otherHandler = new EppQuotaHandler(quotaManager, metrics);
+    final EmbeddedChannel otherChannel = new EmbeddedChannel(otherHandler);
+    otherChannel.attr(CLIENT_CERTIFICATE_HASH_KEY).set(clientCertHash);
+    setProtocol(otherChannel);
+    final DateTime later = now.plus(Duration.standardSeconds(1));
+
+    when(quotaManager.acquireQuota(QuotaRequest.create(clientCertHash)))
+        .thenReturn(QuotaResponse.create(true, clientCertHash, now))
+        .thenReturn(QuotaResponse.create(false, clientCertHash, later));
+
+    // Allows the first channel.
+    assertThat(channel.writeInbound(message)).isTrue();
+    assertThat((Object) channel.readInbound()).isEqualTo(message);
+    assertThat(channel.isActive()).isTrue();
+
+    // Blocks the second channel.
+    OverQuotaException e =
+        assertThrows(OverQuotaException.class, () -> otherChannel.writeInbound(message));
+    assertThat(e).hasMessageThat().contains(clientCertHash);
+    verify(metrics).registerQuotaRejection("epp", clientCertHash);
+    verifyNoMoreInteractions(metrics);
+  }
+}