code: public final Set<ConstraintViolation<Object>> getConstraintViolations() {
          if (constraintViolations == null) {
              return null;
          }
          return Collections.unmodifiableSet(constraintViolations);
      }
docs: Returns the constraint violations.
  
  @return Immutable set of constraint violations or <code>null</code> if only a message is available.