code: public boolean addValidationConstraint(String type, String field, Constraint c) {
  		if (!StringUtils.isBlank(type) && !StringUtils.isBlank(field) &&
  				c != null && !c.getPayload().isEmpty() &&
  				Constraint.isValidConstraintName(c.getName())) {
  			Map<String, Map<String, Map<String, ?>>> fieldMap = getValidationConstraints().get(type);
  			Map<String, Map<String, ?>> consMap;
  			if (fieldMap != null) {
  				consMap = fieldMap.get(field);
  				if (consMap == null) {
  					consMap = new LinkedHashMap<>();
  				}
  			} else {
  				fieldMap = new LinkedHashMap<>();
  				consMap = new LinkedHashMap<>();
  			}
  			consMap.put(c.getName(), c.getPayload());
  			fieldMap.put(field, consMap);
  			getValidationConstraints().put(type, fieldMap);
  			return true;
  		}
  		return false;
  	}
docs: Adds a new constraint to the list of constraints for a given field and type.
  @param type the type
  @param field the field
  @param c the constraint
  @return true if successful