@Override
    public void declareOutputFields(OutputFieldsDeclarer declarer)
    {
        List<String> fields = Lists.newArrayList(FieldName.MESSAGE_KEY, FieldName.MESSAGE_VALUE);

        // Declare default stream
        declarer.declare(new Fields(fields));

        for (String stream : getOutputStreams())
        {
            declarer.declareStream(stream, new Fields(fields));
        }
    }
@ Override public void declareOutputFields ( OutputFieldsDeclarer declarer ) { List < String > fields = Lists . newArrayList ( FieldName . MESSAGE_KEY , FieldName . MESSAGE_VALUE ) ; declarer . declare ( new Fields ( fields ) ) ; for ( String stream : getOutputStreams ( ) ) { declarer . declareStream ( stream , new Fields ( fields ) ) ; } }
Declare output fields and streams.<br>
Declare fields are following.<br>
<ol>
<li>messageKey   : Groupingkey if exists.</li>
<li>messageValue : Message value.</li>
</ol>
Streams are "default" and user setting streams.

@param declarer declarer object