Add framework for customizable WHOIS commands

With some additional changes by Ben McIlwain.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=145447136

java/google/registry/whois/WhoisCommandFactory.java

@@ -0,0 +1,74 @@
+// Copyright 2016 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.whois;
+
+import com.google.common.net.InternetDomainName;
+import google.registry.config.RegistryConfig.ConfigModule;
+import java.net.InetAddress;
+import javax.annotation.Nullable;
+
+/**
+ * A class used to configure WHOIS commands.
+ *
+ * <p>To add custom commands, extend this class, then configure it in
+ * {@link ConfigModule#provideWhoisCommandFactoryClass()}.
+ */
+public class WhoisCommandFactory {
+
+  /** Returns a new {@link WhoisCommand} to perform a domain lookup on the specified domain name. */
+  public final WhoisCommand domainLookup(InternetDomainName domainName) {
+    return domainLookup(domainName, null);
+  }
+
+  /**
+   * Returns a new {@link WhoisCommand} to perform a domain lookup on the specified domain name in
+   * the specified TLD.
+   */
+  public WhoisCommand domainLookup(
+      InternetDomainName domainName, @Nullable InternetDomainName tld) {
+    return new DomainLookupCommand(domainName, tld);
+  }
+
+  /**
+   * Returns a new {@link WhoisCommand} to perform a nameserver lookup on the specified IP address.
+   */
+  public WhoisCommand nameserverLookupByIp(InetAddress inetAddress) {
+    return new NameserverLookupByIpCommand(inetAddress);
+  }
+
+  /**
+   * Returns a new {@link WhoisCommand} to perform a nameserver lookup on the specified host name.
+   */
+  public final WhoisCommand nameserverLookupByHost(InternetDomainName hostName) {
+    return nameserverLookupByHost(hostName, null);
+  }
+
+  /**
+   * Returns a new {@link WhoisCommand} to perform a nameserver lookup on the specified host name in
+   * the specified TLD.
+   */
+  public WhoisCommand nameserverLookupByHost(
+      InternetDomainName hostName, @Nullable InternetDomainName tld) {
+    return new NameserverLookupByHostCommand(hostName, tld);
+  }
+
+  /**
+   * Returns a new {@link WhoisCommand} to perform a registrar lookup on the specified registrar
+   * name.
+   */
+  public WhoisCommand registrarLookup(String registrar) {
+    return new RegistrarLookupCommand(registrar);
+  }
+}