code: public HelpersBuilder addSwitch(boolean caseDefaultIsBreak) {
          builder.put(SWITCH, new SwitchHelper());
          builder.put(CASE, new SwitchHelper.CaseHelper(caseDefaultIsBreak));
          builder.put(DEFAULT, new SwitchHelper.DefaultHelper());
          return this;
      }
docs: Add an instance of {@link SwitchHelper} with the {@value #SWITCH} name.
  Also adds the dependent helpers.
  
  @param caseDefaultIsBreak
  If <code>true</code> the matching case helper terminates the flow by
  default.
  @return self