code: private static <E extends Enum<E>> Class<E> checkBitVectorable(final Class<E> enumClass) {
          final E[] constants = asEnum(enumClass).getEnumConstants();
          Validate.isTrue(constants.length <= Long.SIZE, CANNOT_STORE_S_S_VALUES_IN_S_BITS,
              Integer.valueOf(constants.length), enumClass.getSimpleName(), Integer.valueOf(Long.SIZE));
  
          return enumClass;
      }
docs: Validate that {@code enumClass} is compatible with representation in a {@code long}.
  @param <E> the type of the enumeration
  @param enumClass to check
  @return {@code enumClass}
  @throws NullPointerException if {@code enumClass} is {@code null}
  @throws IllegalArgumentException if {@code enumClass} is not an enum class or has more than 64 values
  @since 3.0.1