QPID-8676 - [Broker-J] NPE when detaching endpoint (#246)

Author: dakirily

broker-core/src/main/java/org/apache/qpid/server/util/CollectionUtils.java

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.qpid.server.util;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Collection utilities
+ */
+public final class CollectionUtils
+{
+    /** Utility class shouldn't be instantiated directly */
+    private CollectionUtils()
+    {
+
+    }
+
+    /**
+     * Returns a fixed-size list backed by the specified array. When array is null, returns an empty list
+     * @param array Array of elements
+     * @return List of elements
+     * @param <T> Element type
+     */
+    public static <T> List<T> nullSafeList(final T[] array)
+    {
+        if (array == null)
+        {
+            return new ArrayList<>();
+        }
+        return Arrays.asList(array);
+    }
+}

broker-plugins/amqp-1-0-protocol/src/main/java/org/apache/qpid/server/protocol/v1_0/TxnCoordinatorReceivingLinkEndpoint.java

@@ -19,7 +19,6 @@
 
 package org.apache.qpid.server.protocol.v1_0;
 
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -50,6 +49,7 @@
 import org.apache.qpid.server.protocol.v1_0.type.transport.Error;
 import org.apache.qpid.server.txn.LocalTransaction;
 import org.apache.qpid.server.txn.ServerTransaction;
+import org.apache.qpid.server.util.CollectionUtils;
 import org.apache.qpid.server.util.ConnectionScopedRuntimeException;
 import org.apache.qpid.server.util.ServerScopedRuntimeException;
 
@@ -121,7 +121,7 @@ else if (command instanceof Discharge)
                             {
                                 outcome = new Accepted();
                             }
-                            else if (Arrays.asList(getSource().getOutcomes()).contains(Rejected.REJECTED_SYMBOL))
+                            else if (CollectionUtils.nullSafeList(getSource().getOutcomes()).contains(Rejected.REJECTED_SYMBOL))
                             {
                                 final Rejected rejected = new Rejected();
                                 rejected.setError(error);