@Retention(RetentionPolicy.RUNTIME)
  private @interface Generates {}

  /**
   * Annotates a method to generate the "empty" instance of a collection. This method should accept
   * no parameter. The value it generates should be unequal to the values generated by methods
   * annotated with {@link Generates}.
   */
  @Target(ElementType.METHOD)
  @Retention(RetentionPolicy.RUNTIME)
  private @interface Empty {}

  @Retention(RetentionPolicy.RUNTIME)
  private @interface Generates {}

  /**
   * Annotates a method to generate the "empty" instance of a collection. This method should accept
   * no parameter. The value it generates should be unequal to the values generated by methods
   * annotated with {@link Generates}.
   */
  @Target(ElementType.METHOD)
  @Retention(RetentionPolicy.RUNTIME)
  private @interface Empty {}