code: public static <D,S> IJMapper<D, S> getMapper(final Class<D> destination,final Class<S> source,final String xml) {
  		return getMapper(destination,source,null,xml);
  	}
docs: Returns an instance of JMapper from cache if exists, in alternative a new instance.
  <br>Taking as input the path to the xml file or the content.
  
  @param destination the Destination Class
  @param source the Source Class
  @param xml xml configuration as content or path format
  @param <D> Destination class
  @param <S> Source Class
  @return the mapper instance