Make Address (& super & subs) Cloneable

* Implement Cloneable in VersionedChecksummedBytes
* Override clone() in VersionedChecksummedBytes
* Override clone() in Address
* Add Unit test file for VersionedChecksummedBytes
* Add clone unit tests for clone for all subclasses
   of VersionedChecksummedBytes

TODO: Consider overriding clone() in DumpedPrivateKey and
      BIP38PrivateKey

core/src/main/java/org/bitcoinj/core/Address.java

@@ -168,4 +168,12 @@ public class Address extends VersionedChecksummedBytes {
         }
         return false;
     }
+
+    /**
+     * This implementation narrows the return type to <code>Address</code>.
+     */
+    @Override
+    public Address clone() throws CloneNotSupportedException {
+        return (Address) super.clone();
+    }
 }

core/src/main/java/org/bitcoinj/core/VersionedChecksummedBytes.java

@@ -31,7 +31,7 @@ import com.google.common.base.Objects;
  * <p>and the result is then Base58 encoded. This format is used for addresses, and private keys exported using the
  * dumpprivkey command.</p>
  */
-public class VersionedChecksummedBytes implements Serializable {
+public class VersionedChecksummedBytes implements Serializable, Cloneable {
     protected final int version;
     protected byte[] bytes;
 
@@ -82,6 +82,19 @@ public class VersionedChecksummedBytes implements Serializable {
     /**
      * Returns the "version" or "header" byte: the first byte of the data. This is used to disambiguate what the
      * contents apply to, for example, which network the key or address is valid on.
+     * {@inheritDoc}
+     *
+     * This implementation narrows the return type to <code>VersionedChecksummedBytes</code>
+     * and allows subclasses to throw <code>CloneNotSupportedException</code> even though it
+     * is never thrown by this implementation.
+     */
+    @Override
+    public VersionedChecksummedBytes clone() throws CloneNotSupportedException {
+        return (VersionedChecksummedBytes) super.clone();
+    }
+
+
+    /**
      *
      * @return A positive number between 0 and 255.
      */

core/src/test/java/org/bitcoinj/core/AddressTest.java

@@ -168,4 +168,14 @@ public class AddressTest {
         Address address = Address.fromP2SHScript(mainParams, p2shScript);
         assertEquals("3N25saC4dT24RphDAwLtD8LUN4E2gZPJke", address.toString());
     }
+
+    @Test
+    public void cloning() throws Exception {
+        Address a = new Address(testParams, HEX.decode("fda79a24e50ff70ff42f7d89585da5bd19d9e5cc"));
+        Address b = a.clone();
+
+        assertEquals(a, b);
+        assertNotSame(a, b);
+    }
+
 }

core/src/test/java/org/bitcoinj/core/DumpedPrivateKeyTest.java

@@ -17,6 +17,7 @@
 package org.bitcoinj.core;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotSame;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -38,4 +39,15 @@ public class DumpedPrivateKeyTest {
                 .readObject();
         assertEquals(key, keyCopy);
     }
+
+    @Test
+    public void cloning() throws Exception {
+        DumpedPrivateKey a = new DumpedPrivateKey(MainNetParams.get(), new ECKey().getPrivKeyBytes(), true);
+        // TODO: Consider overriding clone() in DumpedPrivateKey to narrow the type
+        DumpedPrivateKey b = (DumpedPrivateKey) a.clone();
+
+        assertEquals(a, b);
+        assertNotSame(a, b);
+    }
+
 }

core/src/test/java/org/bitcoinj/core/VersionedChecksummedBytesTest.java

@@ -0,0 +1,55 @@
+/**
+ * Copyright 2014 BitcoinJ Project
+ *
+ * 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 org.bitcoinj.core;
+
+import org.bitcoinj.params.MainNetParams;
+import org.bitcoinj.params.TestNet3Params;
+import org.junit.Test;
+
+import static org.bitcoinj.core.Utils.HEX;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotSame;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+/**
+ *
+ */
+public class VersionedChecksummedBytesTest {
+    static final NetworkParameters testParams = TestNet3Params.get();
+    static final NetworkParameters mainParams = MainNetParams.get();
+
+    @Test
+    public void stringification() throws Exception {
+        // Test a testnet address.
+        VersionedChecksummedBytes a = new VersionedChecksummedBytes(testParams.getAddressHeader(), HEX.decode("fda79a24e50ff70ff42f7d89585da5bd19d9e5cc"));
+        assertEquals("n4eA2nbYqErp7H6jebchxAN59DmNpksexv", a.toString());
+
+        VersionedChecksummedBytes b = new VersionedChecksummedBytes(mainParams.getAddressHeader(), HEX.decode("4a22c3c4cbb31e4d03b15550636762bda0baf85a"));
+        assertEquals("17kzeh4N8g49GFvdDzSf8PjaPfyoD1MndL", b.toString());
+    }
+
+    @Test
+    public void cloning() throws Exception {
+        VersionedChecksummedBytes a = new VersionedChecksummedBytes(testParams.getAddressHeader(), HEX.decode("fda79a24e50ff70ff42f7d89585da5bd19d9e5cc"));
+        VersionedChecksummedBytes b = a.clone();
+
+        assertEquals(a, b);
+        assertNotSame(a, b);
+    }
+
+}

core/src/test/java/org/bitcoinj/crypto/BIP38PrivateKeyTest.java

@@ -28,6 +28,7 @@ import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotSame;
 
 public class BIP38PrivateKeyTest {
 
@@ -157,4 +158,15 @@ public class BIP38PrivateKeyTest {
                 .readObject();
         assertEquals(key, keyCopy);
     }
+
+    @Test
+    public void cloning() throws Exception {
+        BIP38PrivateKey a = new BIP38PrivateKey(TESTNET, "6PfMmVHn153N3x83Yiy4Nf76dHUkXufe2Adr9Fw5bewrunGNeaw2QCpifb");
+        // TODO: Consider overriding clone() in BIP38PrivateKey to narrow the type
+        BIP38PrivateKey b = (BIP38PrivateKey) a.clone();
+
+        assertEquals(a, b);
+        assertNotSame(a, b);
+    }
+
 }