Add license header

Signed-off-by: Craig Perkins <cwperx@amazon.com>

Author: cwperks

src/integrationTest/java/org/opensearch/security/http/RolesMappingTests.java

@@ -1,3 +1,12 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ *
+ */
 package org.opensearch.security.http;
 
 import java.util.List;