docs: @Override
      protected void initializeTokenStream( DdlTokenStream tokens ) {
          super.initializeTokenStream(tokens);
          tokens.registerKeyWords(CUSTOM_KEYWORDS);
          tokens.registerStatementStartPhrase(ALTER_PHRASES);
          tokens.registerStatementStartPhrase(CREATE_PHRASES);
          tokens.registerStatementStartPhrase(DROP_PHRASES);
          tokens.registerStatementStartPhrase(SET_PHRASES);
          tokens.registerStatementStartPhrase(MISC_PHRASES);
      }