https://github.com/google/guice/guice: Guice is a lightweight dependency injection framework for Java 6 and above (Google, Inc.) 
/*
 * Copyright (C) 2015 Google Inc.
 *
 * 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.inject.multibindings;

import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

import com.google.inject.Module;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;


Annotates methods of a Module to add items to a MapBinder. The method's return type, binding annotation and additional key annotation determines what Map this will contribute to. For example, 
@ProvidesIntoMap @StringMapKey("Foo") @Named("plugins") Plugin provideFooUrl(FooManager fm) { return fm.getPlugin(); } @ProvidesIntoMap @StringMapKey("Bar") @Named("plugins") Plugin provideBarUrl(BarManager bm) { return bm.getPlugin(); } 
 will add two items to the @Named("plugins") Map<String, Plugin> map. The key 'Foo' will map to the provideFooUrl method, and the key 'Bar' will map to the provideBarUrl method. The values are bound as providers and will be evaluated at injection time. 
Because the key is specified as an annotation, only Strings, Classes, enums, primitive types
and annotation instances are supported as keys.

Author:sameb@google.com (Sam Berlin)
Since:4.0
/**
 * Annotates methods of a {@link Module} to add items to a {@link MapBinder}. The method's return
 * type, binding annotation and additional key annotation determines what Map this will contribute
 * to. For example,
 *
 * <pre>
 * {@literal @}ProvidesIntoMap
 * {@literal @}StringMapKey("Foo")
 * {@literal @}Named("plugins")
 * Plugin provideFooUrl(FooManager fm) { return fm.getPlugin(); }
 *
 * {@literal @}ProvidesIntoMap
 * {@literal @}StringMapKey("Bar")
 * {@literal @}Named("plugins")
 * Plugin provideBarUrl(BarManager bm) { return bm.getPlugin(); }
 * </pre>
 *
 * will add two items to the {@code @Named("plugins") Map<String, Plugin>} map. The key 'Foo' will
 * map to the provideFooUrl method, and the key 'Bar' will map to the provideBarUrl method. The
 * values are bound as providers and will be evaluated at injection time.
 *
 * <p>Because the key is specified as an annotation, only Strings, Classes, enums, primitive types
 * and annotation instances are supported as keys.
 *
 * @author sameb@google.com (Sam Berlin)
 * @since 4.0
 */
@Documented
@Target(METHOD)
@Retention(RUNTIME)
public @interface ProvidesIntoMap {}