org.apache.druid.guice.annotations.ExtensionPoint Maven / Gradle / Ivy
/*
* 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.druid.guice.annotations;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Signifies that the annotated type is an extension point. Extension points are interfaces or non-final classes that
* may be subclassed in extensions in order to add functionality to Druid. Extension points may change in breaking ways
* only between major Druid release lines (e.g. 0.10.x -> 0.11.0), but otherwise must remain stable. Extension points
* may change at any time in non-breaking ways, however, such as by adding new default methods to an interface.
*
* All public and protected fields, methods, and constructors of annotated classes and interfaces are considered
* stable in this sense. If a class is not annotated, but an individual field, method, or constructor is
* annotated, then only that particular field, method, or constructor is considered an extension API.
*
* Extension points are all considered public APIs in the sense of {@link PublicApi}, even if not explicitly annotated
* as such.
*
* Note that there are number of injectable interfaces that are not annotated with {@code ExtensionPoint}. You may
* still extend these interfaces in extensions, but your extension may need to be recompiled even for a minor
* update of Druid.
*
* @see PublicApi
*/
@Target({ElementType.TYPE})
@Retention(RetentionPolicy.SOURCE)
public @interface ExtensionPoint
{
}