code: public MLArray getField(String name, int index)
      {
      	if (mlStructArray.isEmpty()) {
      		return null;
      	}
          return mlStructArray.get(index).get(name);
      }
docs: Gets a value of the field described by name from index'th struct
  in struct array or null if the field doesn't exist.
  
  @param name
  @param index
  @return value of the field or null if the field doesn't exist