function ConnectionImpl() {
  ElementImpl.call(this);

  /**
   * The element this connection originates from
   *
   * @name ConnectionImpl#source
   * @type Element
   */
  outgoingRefs.bind(this, 'source');

  /**
   * The element this connection points to
   *
   * @name ConnectionImpl#target
   * @type Element
   */
  incomingRefs.bind(this, 'target');
}
A connection between two elements

@class
@constructor

@extends ElementImpl