code: public static <T> String marshal(final T data, final Class<?>... classesToBeBound) {
          return marshal(data, null, classesToBeBound);
      }
docs: Marshals the given data. A <code>null</code> data argument returns <code>null</code>.
  
  @param data
  Data to serialize or <code>null</code>.
  @param classesToBeBound
  List of java classes to be recognized by the {@link JAXBContext} - Cannot be <code>null</code>.
  
  @return XML data or <code>null</code>.
  
  @param <T>
  Type of the data.