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.

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

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

@@ -0,0 +1,95 @@
+// 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 io.netty.channel.Channel;
+import io.netty.handler.ssl.SslHandler;
+import io.netty.handler.ssl.util.SelfSignedCertificate;
+import java.math.BigInteger;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.SecureRandom;
+import java.security.Security;
+import java.security.cert.X509Certificate;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Date;
+import javax.net.ssl.SSLSession;
+import javax.security.auth.x500.X500Principal;
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import org.bouncycastle.x509.X509V3CertificateGenerator;
+
+/**
+ * Utility class that provides methods used by {@link SslClientInitializerTest} and {@link
+ * SslServerInitializerTest}.
+ */
+public class SslInitializerTestUtils {
+
+  static {
+    Security.addProvider(new BouncyCastleProvider());
+  }
+
+  public static KeyPair getKeyPair() throws Exception {
+    KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA", "BC");
+    keyPairGenerator.initialize(2048, new SecureRandom());
+    return keyPairGenerator.generateKeyPair();
+  }
+
+  /**
+   * Signs the given key pair with the given self signed certificate.
+   *
+   * @return signed public key (of the key pair) certificate
+   */
+  public static X509Certificate signKeyPair(
+      SelfSignedCertificate ssc, KeyPair keyPair, String hostname) throws Exception {
+    X509V3CertificateGenerator certGen = new X509V3CertificateGenerator();
+    X500Principal dnName = new X500Principal("CN=" + hostname);
+    certGen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis()));
+    certGen.setSubjectDN(dnName);
+    certGen.setIssuerDN(ssc.cert().getSubjectX500Principal());
+    certGen.setNotBefore(Date.from(Instant.now().minus(Duration.ofDays(1))));
+    certGen.setNotAfter(Date.from(Instant.now().plus(Duration.ofDays(1))));
+    certGen.setPublicKey(keyPair.getPublic());
+    certGen.setSignatureAlgorithm("SHA256WithRSAEncryption");
+    return certGen.generate(ssc.key(), "BC");
+  }
+
+  /**
+   * Verifies tha the SSL channel is established as expected, and also sends a message to the server
+   * and verifies if it is echoed back correctly.
+   *
+   * @param certs The certificate that the server should provide.
+   * @return The SSL session in current channel, can be used for further validation.
+   */
+  static SSLSession setUpSslChannel(
+      Channel channel,
+      X509Certificate... certs)
+      throws Exception {
+    SslHandler sslHandler = channel.pipeline().get(SslHandler.class);
+    // Wait till the handshake is complete.
+    sslHandler.handshakeFuture().get();
+
+    assertThat(channel.isActive()).isTrue();
+    assertThat(sslHandler.handshakeFuture().isSuccess()).isTrue();
+    assertThat(sslHandler.engine().getSession().isValid()).isTrue();
+    assertThat(sslHandler.engine().getSession().getPeerCertificates())
+        .asList()
+        .containsExactlyElementsIn(certs);
+    // Returns the SSL session for further assertion.
+    return sslHandler.engine().getSession();
+  }
+}