org.apache.tapestry5.ioc.annotations

## Annotation Type Optional

-     @Target(value=METHOD)
      @Retention(value=RUNTIME)
      @Documented
      @UseWith(value=MODULE)
      public @interface Optional

  Marks a service contribution method within a module as being optional: it is not an error if the contribution does not match against an actual service. In that case, the method will simply never be invoked. This is occasionally useful when a module is designed to work with another module if the second module is present. Without optional contributions, you would see hard errors when registry is created, and have to create a layer cake of small modules to prevent such errors.
  Since:
    5.3
  See Also:
    `Contribute`, `ContributionDef3.isOptional()`

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