Error in Java Mapping

Dear Experts,

I am working on a scenario to convert the JSON data format as response to XML format in SAP PI 7.4. When I completed the work in NWDS I am receiving no error as it is run as a standalone JAVA application.

After importing in to ESR and running for test I am receiving error as :

Does not implement the required interface com.sap.aii.mapping.api.StreamTransformation or does not enhance the class com.sap.aii.mapping.api.AbstractTransformation.

I followed and implemented from some SCN example but still not able to solve the issue. Below is my code..

package com.cms;

import java.io.RandomAccessFile;

import java.io.StringWriter;

import java.util.List;

import javax.xml.parsers.DocumentBuilder;

import javax.xml.parsers.DocumentBuilderFactory;

import javax.xml.transform.OutputKeys;

import javax.xml.transform.Transformer;

import javax.xml.transform.TransformerFactory;

import javax.xml.transform.dom.DOMSource;

import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;

import org.w3c.dom.Element;

import org.w3c.dom.Node;

import com.cms.model.Item;

import com.cms.model.Items;

import com.cms.model.Response;

import com.fasterxml.jackson.databind.ObjectMapper;

import com.sap.aii.mapping.api.AbstractTransformation;

import com.sap.aii.mapping.api.StreamTransformationException;

import com.sap.aii.mapping.api.TransformationInput;

import com.sap.aii.mapping.api.TransformationOutput;

import java.io*;

public class json2xml extends AbstractTransformation {

  public void transform(TransformationInput arg0, TransformationOutput arg1)

  throws StreamTransformationException

        {

         arg0.getInputPayload().getInputStream();

  arg1.getOutputPayload().getOutputStream();

         }

  public void execute(InputStream iStream, OutputStream oStream)

  Response  response = new Response();

  DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();

  DocumentBuilder dBuilder;

  DOMSource source = null;

  try {

  dBuilder = dbFactory.newDocumentBuilder();

  Document doc = dBuilder.newDocument();

      Element rootElement = doc.createElementNS("http://www.cms.com/items", "Items");

  //append root element to document

  doc.appendChild(rootElement);

  // read source from file system

  String parentDirectory = "C:/Users/Desktop/XML2JSON/src/";

  String file = "JSON.txt";

  RandomAccessFile f = new RandomAccessFile(parentDirectory+file, "r");

  byte[] jsondata = new byte[(int)f.length()];

  f.read(jsondata);

  ObjectMapper objectMapper = new ObjectMapper();      

  response = objectMapper.readValue(jsondata, Response.class);

  //append first child element to root element

  rootElement.appendChild(getItem(doc, response.getItems()));

  //for output to file, console

  TransformerFactory transformerFactory = TransformerFactory.newInstance();

  Transformer transformer = transformerFactory.newTransformer();

  //for pretty print

  transformer.setOutputProperty(OutputKeys.INDENT, "yes");

  source = new DOMSource(doc);

  //write to console or file

  StreamResult result = new StreamResult(new StringWriter());

  transformer.transform(source, result);

  System.out.println(result.getWriter());

  } catch (Exception e) {

             e.printStackTrace();

         }

  }

  //utility method to create text node

    private static Node getItemElements(Document doc, Element element, String name, String value) {

        Element node = doc.createElement(name);

        node.appendChild(doc.createTextNode(value));

        return node;

    }

  private static Node getItem(Document doc, List<Items> items) {

        Element item = doc.createElement("item");

        Item _item = items.get(0).getItem();

        item.appendChild(getItemElements(doc, item,"WFID",_item.getWFID()));

        item.appendChild(getItemElements(doc, item,"Subject",_item.getSubject()));

        item.appendChild(getItemElements(doc, item,"DocumentID",_item.getDocumentID()));

        item.appendChild(getItemElements(doc, item,"Sender",_item.getSender()));

        item.appendChild(getItemElements(doc, item,"SenderDomainName",_item.getSenderDomainName()));

        item.appendChild(getItemElements(doc, item,"Action",_item.getAction()));

        item.appendChild(getItemElements(doc, item,"Date",_item.getDate()));

        item.appendChild(getItemElements(doc, item,"DocumentClassID",_item.getDocumentClassID()));

        item.appendChild(getItemElements(doc, item,"Comment",_item.getComment()));

        item.appendChild(getItemElements(doc, item,"WobNum",_item.getWobNum()));

        item.appendChild(getItemElements(doc, item,"MainSource",_item.getMainSource()));

        item.appendChild(getItemElements(doc, item,"SubSource",_item.getSubSource()));

        item.appendChild(getItemElements(doc, item,"PriorityLevel",_item.getPriorityLevel()));

        item.appendChild(getItemElements(doc, item,"IsGroupMail",_item.getIsGroupMail()));

        item.appendChild(getItemElements(doc, item,"IsOpen",_item.getIsOpen()));

        item.appendChild(getItemElements(doc, item,"DaysCount",_item.getDaysCount()));

        return item;

    }

}

Please help to rectify the code error?

Regards