public R paramsToJsonEntity(){
  try {
    mHttpEntity=createJsonStreamerEntity(null);
  }
 catch (  IOException e) {
    e.printStackTrace();
  }
  return (R)this;
}

public R paramsToJsonEntity ( ) { try { mHttpEntity = createJsonStreamerEntity ( null ) ; } catch ( IOException e ) { e . printStackTrace ( ) ; } return ( R ) this ; }
convert params to json entity .
