add missing license header

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1786962 13f79535-47bb-0310-9956-ffa450edef68

src/ooxml/testcases/org/apache/poi/ss/formula/functions/TestSumifsXSSF.java

@@ -1,3 +1,22 @@
+/*
+ *  ====================================================================
+ *    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.poi.ss.formula.functions;
 
 import static org.junit.Assert.assertEquals;