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.spi;

import com.google.inject.Binder;
import com.google.inject.Key;
import java.lang.annotation.Annotation;
import java.util.Set;


Allows extensions to scan modules for annotated methods and bind those methods as providers, similar to @Provides methods. 
Since:4.0
/**
 * Allows extensions to scan modules for annotated methods and bind those methods as providers,
 * similar to {@code @Provides} methods.
 *
 * @since 4.0
 */
public abstract class ModuleAnnotatedMethodScanner {

  
Returns the annotations this should scan for. Every method in the module that has one of these
annotations will create a Provider binding, with the return value of the binding being what's
provided and the parameters of the method being dependencies of the provider.

/**
   * Returns the annotations this should scan for. Every method in the module that has one of these
   * annotations will create a Provider binding, with the return value of the binding being what's
   * provided and the parameters of the method being dependencies of the provider.
   */
  public abstract Set<? extends Class<? extends Annotation>> annotationClasses();

  
Prepares a method for binding. This key parameter is the key discovered from looking at the binding annotation and return value of the method. Implementations can modify the key to instead bind to another key. For example, Multibinder may want to change @ProvidesIntoSet String provideFoo() to bind into a unique Key within the multibinder instead of binding String. 
The injection point and annotation are provided in case the implementation wants to set the key based on the property of the annotation or if any additional preparation is needed for any of the dependencies. The annotation is guaranteed to be an instance of one the classes returned by annotationClasses. 
If injectionPoint represents an abstract method, null must be returned from this method. This scanner can use binder to bind alternative bindings in place of the abstract method. In all other cases, this method may not return null. 
/**
   * Prepares a method for binding. This {@code key} parameter is the key discovered from looking at
   * the binding annotation and return value of the method. Implementations can modify the key to
   * instead bind to another key. For example, Multibinder may want to change
   * {@code @ProvidesIntoSet String provideFoo()} to bind into a unique Key within the multibinder
   * instead of binding {@code String}.
   *
   * <p>The injection point and annotation are provided in case the implementation wants to set the
   * key based on the property of the annotation or if any additional preparation is needed for any
   * of the dependencies. The annotation is guaranteed to be an instance of one the classes returned
   * by {@link #annotationClasses}.
   *
   * <p>If {@code injectionPoint} represents an {@code abstract} method, {@code null} must be
   * returned from this method. This scanner can use {@code binder} to bind alternative bindings in
   * place of the abstract method. In all other cases, this method may not return null.
   */
  public abstract <T> Key<T> prepareMethod(
      Binder binder, Annotation annotation, Key<T> key, InjectionPoint injectionPoint);
}