Support multiple versions of the EPP Fee Extension

We want to support multiple versions of the fee extension, to allow new features while maintaining backward compatibility. This CL extends the framework and adds one new version, 0.11 (spec version 7), to the existing version 0.6 (spec version 3). A follow-on CL will add version 0.12 (spec version 8).

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=127849044

java/google/registry/model/domain/fee06/FeeCheckCommandExtensionV06.java

@@ -0,0 +1,65 @@
+// Copyright 2016 The Domain Registry 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.model.domain.fee06;
+
+import static google.registry.util.CollectionUtils.nullToEmptyImmutableCopy;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import google.registry.model.ImmutableObject;
+import google.registry.model.domain.fee.FeeCheckCommandExtension;
+import google.registry.model.domain.fee.FeeCheckResponseExtensionItem;
+import java.util.Set;
+import javax.xml.bind.annotation.XmlElement;
+import javax.xml.bind.annotation.XmlRootElement;
+import org.joda.money.CurrencyUnit;
+
+/** Version 0.6 of the fee extension that may be present on domain check commands. */
+@XmlRootElement(name = "check")
+public class FeeCheckCommandExtensionV06 extends ImmutableObject
+    implements FeeCheckCommandExtension<
+        FeeCheckCommandExtensionItemV06,
+        FeeCheckResponseExtensionV06> {
+  
+  @XmlElement(name = "domain")
+  Set<FeeCheckCommandExtensionItemV06> items;
+
+  @Override
+  public boolean isCurrencySupported() {
+    return false;
+  }
+
+  @Override
+  public CurrencyUnit getCurrency() {
+    throw new UnsupportedOperationException("Currency not supported");
+  }
+
+  @Override
+  public ImmutableSet<FeeCheckCommandExtensionItemV06> getItems() {
+    return nullToEmptyImmutableCopy(items);
+  }
+
+  @Override
+  public FeeCheckResponseExtensionV06 createResponse(
+      ImmutableList<? extends FeeCheckResponseExtensionItem> items) {
+    ImmutableList.Builder<FeeCheckResponseExtensionItemV06> builder = new ImmutableList.Builder<>();
+    for (FeeCheckResponseExtensionItem item : items) {
+      if (item instanceof FeeCheckResponseExtensionItemV06) {
+        builder.add((FeeCheckResponseExtensionItemV06) item);
+      }
+    }
+    return FeeCheckResponseExtensionV06.create(builder.build());
+  }
+}