code: public Command compile(Config morphlineConfig, MorphlineContext morphlineContext, Command finalChild) {
      if (finalChild == null) {
        finalChild = new DropRecordBuilder().build(null, null, null, morphlineContext);
      }
      return new PipeBuilder().build(morphlineConfig, null, finalChild, morphlineContext);
    }
docs: Compiles the given morphline config using the given morphline context. The returned command
  will feed records into finalChild or into /dev/null if finalChild is null.