public static InputOperatorSpec createInputOperatorSpec(
      String streamId, Serde keySerde, Serde valueSerde,
      InputTransformer transformer, boolean isKeyed, String opId) {
    return new InputOperatorSpec(streamId, keySerde, valueSerde, transformer, isKeyed, opId);
  }
Creates an {@link InputOperatorSpec} for consuming input.

@param streamId  the stream id for the input stream
@param keySerde  the serde for the input key
@param valueSerde  the serde for the input value
@param transformer the input stream transformer
@param isKeyed  whether the input stream is keyed
@param opId  the unique ID of the operator
@return  the {@link InputOperatorSpec}
samza-core/src/main/java/org/apache/samza/operators/spec/OperatorSpecs.java