fix license

Author: yarinvak

src/main/java/graphql/annotations/directives/DirectiveSchemaVisitor.java

@@ -1,3 +1,15 @@
+/**
+ * Licensed 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
+ */
 /**
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.