code: public void replaceField(String sourceField, String targetField, String oldString, String newString) {
          TransformationStep step = new TransformationStep();
          step.setSourceFields(sourceField);
          step.setTargetField(targetField);
          step.setOperationParameter(TransformationConstants.REPLACE_OLD_PARAM, oldString);
          step.setOperationParameter(TransformationConstants.REPLACE_NEW_PARAM, newString);
          step.setOperationName("replace");
          steps.add(step);
      }
docs: Adds a replace step to the transformation description. The source and the target field need to be of String type.
  Performs standard string replacement on the string of the source field and writes the result to the target field.