code: public Map<String, Map<String, Map<String, Map<String, ?>>>> removeValidationConstraint(String type,
  			String field, String constraintName) {
  		if (StringUtils.isBlank(type) || StringUtils.isBlank(field) || StringUtils.isBlank(constraintName)) {
  			return Collections.emptyMap();
  		}
  		return getEntity(invokeDelete(Utils.formatMessage("_constraints/{0}/{1}/{2}", type,
  				field, constraintName), null), Map.class);
  	}
docs: Removes a validation constraint for a given field.
  @param type a type
  @param field a field name
  @param constraintName the name of the constraint to remove
  @return a map containing all validation constraints for this type.