docs: public static <T> void isEquals( final T argument,
                                       String argumentName,
                                       final T object,
                                       String objectName ) {
          if (argument == null) {
              if (object == null) return;
              // fall through ... one is null
          } else {
              if (argument.equals(object)) return;
              // fall through ... they are not equal
          }
          if (objectName == null) objectName = getObjectName(object);
          throw new IllegalArgumentException(CommonI18n.argumentMustBeEquals.text(argumentName, objectName));
      }