add license header
diff --git a/vxquery-core/src/main/java/org/apache/vxquery/datamodel/accessors/ArrayBackedValueStoragePool.java b/vxquery-core/src/main/java/org/apache/vxquery/datamodel/accessors/ArrayBackedValueStoragePool.java
index 4c432a9..37a3e40 100644
--- a/vxquery-core/src/main/java/org/apache/vxquery/datamodel/accessors/ArrayBackedValueStoragePool.java
+++ b/vxquery-core/src/main/java/org/apache/vxquery/datamodel/accessors/ArrayBackedValueStoragePool.java
@@ -1,3 +1,19 @@
+/*
+ * 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.vxquery.datamodel.accessors;
import org.apache.hyracks.data.std.util.ArrayBackedValueStorage;
