code: protected List<Name> parseSupertypes( TokenStream tokens ) {
          if (tokens.canConsume('>')) {
              // There is at least one supertype ...
              return parseNameList(tokens);
          }
          return Collections.emptyList();
      }
docs: Parse an optional list of supertypes if they appear next on the token stream.
  
  @param tokens the tokens containing the supertype names; never null
  @return the list of supertype names; never null, but possibly empty
  @throws ParsingException if there is a problem parsing the content