@Override
  public ScheduledFunction getScheduledFn() {
    return this.mapFn instanceof ScheduledFunction ? (ScheduledFunction) this.mapFn : null;
  }
The spec for an operator that transforms each input message to a single output message.

@param <M> type of input message
@param <OM> type of output messages
samza-core/src/main/java/org/apache/samza/operators/spec/MapOperatorSpec.java