docs: @Override
      public Boolean convert(String v) {
          if (v == null) {
              return null;
          }
          if (v.equalsIgnoreCase("true") || v.equalsIgnoreCase("yes") || v.equalsIgnoreCase("y") || v.equalsIgnoreCase("on") || v.equalsIgnoreCase("1")) {
              return Boolean.TRUE;
          } else {
              return Boolean.FALSE;
          }
      }