code: function GetDocumentRequest(properties) {
                      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 GetDocumentRequest.
  @memberof google.firestore.v1
  @interface IGetDocumentRequest
  @property {string|null} [name] GetDocumentRequest name
  @property {google.firestore.v1.IDocumentMask|null} [mask] GetDocumentRequest mask
  @property {Uint8Array|null} [transaction] GetDocumentRequest transaction
  @property {google.protobuf.ITimestamp|null} [readTime] GetDocumentRequest readTime
   
  Constructs a new GetDocumentRequest.
  @memberof google.firestore.v1
  @classdesc Represents a GetDocumentRequest.
  @implements IGetDocumentRequest
  @constructor
  @param {google.firestore.v1.IGetDocumentRequest=} [properties] Properties to set