Fix #634: NPE when default file persistence tries to restore persisted data using only header data array.

Signed-off-by: Matt Magoffin <matt@solarnetwork.net>

Author: msqr

org.eclipse.paho.client.mqttv3.test/src/test/java/org/eclipse/paho/client/mqttv3/test/internal/MqttPersistentDataTest.java

@@ -0,0 +1,55 @@
+/** Copyright (c)  2014 IBM Corp.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * and Eclipse Distribution License v1.0 which accompany this distribution. 
+ *
+ * The Eclipse Public License is available at 
+ *    http://www.eclipse.org/legal/epl-v10.html
+ * and the Eclipse Distribution License is available at 
+ *   http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ *******************************************************************************/
+
+package org.eclipse.paho.client.mqttv3.test.internal;
+
+import java.util.logging.Logger;
+
+import org.eclipse.paho.client.mqttv3.internal.MqttPersistentData;
+import org.eclipse.paho.client.mqttv3.test.logging.LoggingUtilities;
+import org.eclipse.paho.client.mqttv3.test.utilities.Utility;
+import org.junit.AfterClass;
+import org.junit.Assert;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+/**
+ * Tests mqtt topic wildcards
+ */
+public class MqttPersistentDataTest {
+
+	static final Class<?> cclass = MqttPersistentDataTest.class;
+	private static final String className = cclass.getName();
+	private static final Logger log = Logger.getLogger(className);
+
+	@BeforeClass
+	public static void setUpBeforeClass() throws Exception {
+		String methodName = Utility.getMethodName();
+		LoggingUtilities.banner(log, cclass, methodName);
+	}
+
+	@AfterClass
+	public static void tearDownAfterClass() throws Exception {
+		String methodName = Utility.getMethodName();
+		LoggingUtilities.banner(log, cclass, methodName);
+	}
+
+	@Test
+	public void testConstructWithNullPayload() throws Exception {
+	  byte[] head = new byte[] {1,2,3};
+	  MqttPersistentData data = new MqttPersistentData("foo", head, 0, head.length, null, 0, 0);
+	  Assert.assertArrayEquals("Header data", head, data.getHeaderBytes());
+	  Assert.assertNotSame("Header cloned", head, data.getHeaderBytes());
+	}
+
+}

org.eclipse.paho.client.mqttv3/src/main/java/org/eclipse/paho/client/mqttv3/internal/MqttPersistentData.java

@@ -60,7 +60,7 @@ public MqttPersistentData( String key,
 		this.header  = header.clone();
 		this.hOffset = hOffset;
 		this.hLength = hLength;
-		this.payload = payload.clone();
+		this.payload = (payload != null ? payload.clone() : null);
 		this.pOffset = pOffset;
 		this.pLength = pLength;
 	}