https://github.com/google/guava/guava: Guava is a suite of core and expanded libraries that include utility classes, google's collections, io classes, and much much more. 
/*
 * Copyright (C) 2006 The Guava Authors
 *
 * 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.google.common.annotations;


Annotates a program element that exists, or is more widely visible than otherwise necessary, only
for use in test code.

Author:Johannes Henkel
/**
 * Annotates a program element that exists, or is more widely visible than otherwise necessary, only
 * for use in test code.
 *
 * @author Johannes Henkel
 */
@GwtCompatible
public @interface VisibleForTesting {
}