code: function Constraint(constraintName, constraintPayload) {
  	var name = constraintName;
  	var payload = constraintPayload;
  
  	/**
  	 * The constraint name.
  	 * @returns {String} a name
  	 */
  	this.getName = function () {
  		return name;
  	};
  
  	/**
  	 * Sets the name of the constraint.
  	 * @param {String} n name
  	 */
  	this.setName = function (n) {
  		name = n;
  	};
  
  	/**
  	 * The payload (a map)
  	 * @returns {Object} an object
  	 */
  	this.getPayload = function () {
  		return payload;
  	};
  
  	/**
  	 * Sets the payload.
  	 * @param {Object} p the payload object
  	 */
  	this.setPayload = function (p) {
  		payload = p;
  	};
  }
docs: Represents a validation constraint.
  @author Alex Bogdanovski [alex@erudika.com]
  @param {String} constraintName name
  @param {Object} constraintPayload payload
  @returns {Constraint}