In StreamProcessor descriptor defaultPartitions is not taken in account

When contributing a StreamProcessor the default number of partitions  for streams is not taken in account and is always 4.

For instance in the below example the input stream will have 4 partitions instead of the 2 expected:

<streamProcessor name="myStreamProcessor" class="..." defaultPartitions="2" logConfig="default">
 <computation name="myComputation" concurrency="1" />
  <stream name="input" codec="avro" /> 

Note that specifying the number of partition at the Stream level do work as a workaround:

<stream name="input" codec="avro" partitions="2" />