public Map<String, String> getConfig() {
    return config;
  }
Copies this StreamSpec, but applies a new partitionCount.

This method is not static s.t. subclasses can override it.

@param partitionCount  The partitionCount for the returned StreamSpec.
@return                A copy of this StreamSpec with the specified partitionCount.
samza-api/src/main/java/org/apache/samza/system/StreamSpec.java