code: function(terria, pointMovedCallback) {
    this._terria = terria;
    this._setUp = false;
    this.type = "Cesium";
  
    /**
     * Callback that occurs when point is moved. Function takes a CustomDataSource which is a list of PointEntities.
     * @type {PointMovedCallback}
     * @default undefined
     */
    this._pointMovedCallback = pointMovedCallback;
  
    /**
     * List of entities that can be dragged, which is populated with user-created points only.
     * @type {CustomDataSource}
     */
    this._draggableObjects = new CustomDataSource();
  
    /**
     * Whether user is currently dragging point.
     * @type {Bool}
     */
    this._dragInProgress = false;
  
    /**
     * For determining whether a drag has just occurred, to avoid deleting a point at the end of the drag.
     * @type {Number}
     */
    this.dragCount = 0;
  }
docs: Callback for when a point is moved.
  @callback PointMovedCallback
  @param {CustomDataSource} customDataSource Contains all point entities that user has selected so far
   
  For letting user drag existing points in Cesium ViewerModes only.
  
  @alias CesiumDragPoints
  @constructor
  
  @param {Terria} terria The Terria instance.
  @param {PointMovedCallback} pointMovedCallback A function that is called when a point is moved.