code: function TargetChange(properties) {
                      this.targetIds = [];
                      if (properties)
                          for (var keys = Object.keys(properties), i = 0; i < keys.length; ++i)
                              if (properties[keys[i]] != null)
                                  this[keys[i]] = properties[keys[i]];
                  }
docs: Properties of a TargetChange.
  @memberof google.firestore.v1
  @interface ITargetChange
  @property {google.firestore.v1.TargetChange.TargetChangeType|null} [targetChangeType] TargetChange targetChangeType
  @property {Array.<number>|null} [targetIds] TargetChange targetIds
  @property {google.rpc.IStatus|null} [cause] TargetChange cause
  @property {Uint8Array|null} [resumeToken] TargetChange resumeToken
  @property {google.protobuf.ITimestamp|null} [readTime] TargetChange readTime
   
  Constructs a new TargetChange.
  @memberof google.firestore.v1
  @classdesc Represents a TargetChange.
  @implements ITargetChange
  @constructor
  @param {google.firestore.v1.ITargetChange=} [properties] Properties to set