Missing header.

hipparchus-core/src/test/java/org/hipparchus/analysis/differentiation/FieldDerivativeTest.java

@@ -1,3 +1,20 @@
+/*
+ * Licensed to the Hipparchus project under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The Hipparchus 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
+ *
+ *      https://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.hipparchus.analysis.differentiation;
 
 import org.hipparchus.Field;
@@ -327,4 +344,4 @@ public boolean equals(Object obj) {
         }
     }
 
-}
+}