Merge pull request #1866, clarify license for codes referencing thirdparty repositories.

Clarify netty License.
diff --git a/LICENSE b/LICENSE
index 7b279f1..685172e 100644
--- a/LICENSE
+++ b/LICENSE
@@ -263,4 +263,13 @@
 
  * com.google.common.util.concurrent.ExecutionList
  * com.google.common.util.concurrent.ListenableFuture
- * com.google.common.util.concurrent.ListenableFutureTask
\ No newline at end of file
+ * com.google.common.util.concurrent.ListenableFutureTask
+
+For the package com.alibaba.dubbo.common.threadlocal:
+
+This product contains a modified portion of 'Netty', an event-driven asynchronous network application framework also
+ under a "Apache License 2.0" license, see https://github.com/netty/netty/blob/4.1/LICENSE.txt:
+
+ * io.netty.util.concurrent.FastThreadLocal
+ * io.netty.util.internal.InternalThreadLocalMap
+
diff --git a/dubbo-common/src/main/java/com/alibaba/dubbo/common/threadlocal/InternalThreadLocal.java b/dubbo-common/src/main/java/com/alibaba/dubbo/common/threadlocal/InternalThreadLocal.java
index d3d6489..bbf412d 100644
--- a/dubbo-common/src/main/java/com/alibaba/dubbo/common/threadlocal/InternalThreadLocal.java
+++ b/dubbo-common/src/main/java/com/alibaba/dubbo/common/threadlocal/InternalThreadLocal.java
@@ -1,18 +1,17 @@
 /*
- * 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
+ * Copyright 2014 The Netty Project
  *
- *     http://www.apache.org/licenses/LICENSE-2.0
+ * The Netty Project 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.
+ * 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 com.alibaba.dubbo.common.threadlocal;
diff --git a/dubbo-common/src/main/java/com/alibaba/dubbo/common/threadlocal/InternalThreadLocalMap.java b/dubbo-common/src/main/java/com/alibaba/dubbo/common/threadlocal/InternalThreadLocalMap.java
index e2aa0fd..6b0300b 100644
--- a/dubbo-common/src/main/java/com/alibaba/dubbo/common/threadlocal/InternalThreadLocalMap.java
+++ b/dubbo-common/src/main/java/com/alibaba/dubbo/common/threadlocal/InternalThreadLocalMap.java
@@ -1,18 +1,17 @@
 /*
- * 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
+ * Copyright 2014 The Netty Project
  *
- *     http://www.apache.org/licenses/LICENSE-2.0
+ * The Netty Project 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.
+ * 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 com.alibaba.dubbo.common.threadlocal;
diff --git a/pom.xml b/pom.xml
index c8536ae..fa9992f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -494,6 +494,9 @@
                                 <exclude>**/resources/META-INF/**</exclude>
                                 <!-- exclude the hessian-lite files -->
                                 <exclude>**/com/caucho/hessian/**</exclude>
+                                <!-- exclude the internal threadlocal files -->
+                                <exclude>**/com/alibaba/common/threadlocal/InternalThreadLocal.java</exclude>
+                                <exclude>**/com/alibaba/common/threadlocal/InternalThreadLocalMap.java</exclude>
                             </excludes>
                         </configuration>
                     </execution>