Add mapper to import domains from RDE deposits

With some additional cleanup by Ben McIlwain.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=146695665

java/google/registry/xjc/JaxbFragment.java

@@ -0,0 +1,106 @@
+// 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.xjc;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import google.registry.xml.XmlException;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+
+/**
+ * JAXB element wrapper for java object serialization.
+ *
+ * Instances of {@link JaxbFragment} wrap a non-serializable JAXB element instance, and provide
+ * hooks into the java object serialization process that allow the elements to be safely
+ * marshalled and unmarshalled using {@link ObjectOutputStream} and {@link ObjectInputStream},
+ * respectively.
+ */
+public class JaxbFragment<T> implements Serializable {
+
+  private static final long serialVersionUID = 5651243983008818813L;
+
+  private T instance;
+
+  /** Stores a JAXB element in a {@link JaxbFragment} */
+  public static <T> JaxbFragment<T> create(T object) {
+    JaxbFragment<T> fragment = new JaxbFragment<>();
+    fragment.instance = object;
+    return fragment;
+  }
+
+  /** Serializes a JAXB element into xml bytes. */
+  private static <T> byte[] freezeInstance(T instance) throws IOException {
+    try {
+      ByteArrayOutputStream bout = new ByteArrayOutputStream();
+      XjcXmlTransformer.marshalLenient(instance, bout, UTF_8);
+      return bout.toByteArray();
+    } catch (XmlException e) {
+      throw new IOException(e);
+    }
+  }
+
+  /** Deserializes a JAXB element from xml bytes. */
+  private static <T> T unfreezeInstance(byte[] instanceData, Class<? extends Object> instanceType)
+      throws IOException {
+    try {
+      ByteArrayInputStream bin = new ByteArrayInputStream(instanceData);
+      @SuppressWarnings("unchecked")
+      T instance = (T) XjcXmlTransformer.unmarshal(instanceType, bin);
+      return instance;
+    } catch (XmlException e) {
+      throw new IOException(e);
+    }
+  }
+
+  /**
+   * Retrieves the JAXB element that is wrapped by this fragment.
+   */
+  public T getInstance() {
+    return instance;
+  }
+
+  @Override
+  public String toString() {
+    try {
+      return new String(freezeInstance(instance), UTF_8);
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  private void writeObject(ObjectOutputStream out) throws IOException {
+    // write instanceType, then instanceData
+    out.writeObject(instance.getClass());
+    out.writeObject(freezeInstance(instance));
+  }
+
+  private void readObject(ObjectInputStream in) throws IOException {
+    // read instanceType, then instanceData
+    Class<?> instanceType;
+    byte[] instanceData;
+    try {
+      instanceType = (Class<?>) in.readObject();
+      instanceData = (byte[]) in.readObject();
+    } catch (ClassNotFoundException e) {
+      throw new RuntimeException(e);
+    }
+    instance = unfreezeInstance(instanceData, instanceType);
+  }
+}