Package org.apache.tapestry5.ioc.def

## Interface ContributionDef3

- All Superinterfaces:
    `ContributionDef`, `ContributionDef2`, `Markable`
  All Known Implementing Classes:
    `ContributionDefImpl`

      public interface ContributionDef3
      extends ContributionDef2

  Starting in Tapestry 5.3, contributions could be optional.
  Since:
    5.3
  See Also:
    `Optional`

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `boolean` | `isOptional()` | Is this contribution optional, meaning it is not an error if the service to which the contribution is targetted does not exist.

    - ### Methods inherited from interface org.apache.tapestry5.ioc.def.ContributionDef

      `contribute, contribute, contribute, getServiceId`

    - ### Methods inherited from interface org.apache.tapestry5.ioc.Markable

      `getMarkers, getServiceInterface`

- - ### Method Detail

    - #### isOptional

          boolean isOptional()

      Is this contribution optional, meaning it is not an error if the service to which the contribution is targetted does not exist.