code: function BatchGetDocumentsRequest(properties) {
                      this.documents = [];
                      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 BatchGetDocumentsRequest.
  @memberof google.firestore.v1
  @interface IBatchGetDocumentsRequest
  @property {string|null} [database] BatchGetDocumentsRequest database
  @property {Array.<string>|null} [documents] BatchGetDocumentsRequest documents
  @property {google.firestore.v1.IDocumentMask|null} [mask] BatchGetDocumentsRequest mask
  @property {Uint8Array|null} [transaction] BatchGetDocumentsRequest transaction
  @property {google.firestore.v1.ITransactionOptions|null} [newTransaction] BatchGetDocumentsRequest newTransaction
  @property {google.protobuf.ITimestamp|null} [readTime] BatchGetDocumentsRequest readTime
   
  Constructs a new BatchGetDocumentsRequest.
  @memberof google.firestore.v1
  @classdesc Represents a BatchGetDocumentsRequest.
  @implements IBatchGetDocumentsRequest
  @constructor
  @param {google.firestore.v1.IBatchGetDocumentsRequest=} [properties] Properties to set