[BEAM-887] Make FileBasedSink.getWriterResultCoder abstract

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Not applicable
• Fix Version/s: 0.4.0
• Component/s: sdk-java-core
• Labels: backward-incompatible
• Assignee: Kenneth Knowles
• Reporter: Dan Halperin
• Created: 02/Nov/16 22:49
• Updated: 02/Nov/16 23:14
• Resolved: 02/Nov/16 22:54

Description

FileBasedSink has this function:

    /**
      * Returns a coder for the writer result type.
      */
    public Coder<WriteT> getWriterResultCoder() {
      return null;
    }

It returns null by default, but in practice if this happens then building the pipeline will crash with a NullPointerException. Now that we can make backward-incompatible changes, just make it abstract and force implementations to add this method. (All existing implementations override it already.)