code: static boolean attributeHasEnum(XsdAttribute attribute) {
          List<XsdRestriction> restrictions = getAttributeRestrictions(attribute);
  
          return restrictions != null && restrictions.size() == 1 && restrictions.get(0).getEnumeration() != null && !restrictions.get(0).getEnumeration().isEmpty();
      }
docs: Asserts if the received {@link XsdAttribute} has an associated {@link Enum} class.
  @param attribute The {@link XsdAttribute} object.
  @return Whether the received {@link XsdAttribute} has an associated {@link Enum} or not.