Add liscense for holdoutconfig

Author: muzahidul-opti

core-api/src/main/java/com/optimizely/ab/config/HoldoutConfig.java

@@ -1,9 +1,32 @@
+/**
+ *
+ *    Copyright 2016-2019, 2021, Optimizely and contributors
+ *
+ *    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
+ *    limitations under the License.
+ */
+
+
 package com.optimizely.ab.config;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
-import java.util.*;
-import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * HoldoutConfig manages collections of Holdout objects and their relationships to flags.