geode-core/src/main/java/org/apache/geode/management/cli/Disabled.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for additional information regarding
 * copyright ownership. The ASF 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
 *
 * 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 org.apache.geode.management.cli;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * This annotation disables a {@link org.apache.geode.management.cli.GfshCommand}
 * class from being loaded by the
 * {@link org.apache.geode.management.internal.cli.CommandManager}
 * unless the provided flag value exists in the VM's environment.
 *
 * Because the default value is an empty string, and because {@code System.getProperty("")}
 * invalid, a class annotated with {@code @Disabled} cannot be reached other than explicit
 * instantiation of the class.
 */
@Inherited
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Disabled {
  String unlessPropertyIsSet() default "";
}