code: public void addStep(String operationName, List<String> sourceFields, String targetField,
              Map<String, String> parameters) {
          TransformationStep step = new TransformationStep();
          step.setOperationName(operationName);
          step.setSourceFields(sourceFields.toArray(new String[sourceFields.size()]));
          step.setTargetField(targetField);
          step.setOperationParams(parameters);
          steps.add(step);
      }
docs: Adds a transformation step to this description