code: public void add(HttpFields fields)
      {
          if (fields==null)
              return;
  
          Enumeration enm = fields.getFieldNames();
          while( enm.hasMoreElements() )
          {
              String name = (String)enm.nextElement();
              Enumeration values = fields.getValues(name);
              while(values.hasMoreElements())
                  add(name,(String)values.nextElement());
          }
      }
docs: Add fields from another HttpFields instance.
  Single valued fields are replaced, while all others are added.
  @param fields