code: private UnaryCallable<BulkMutation, Void> createBulkMutateRowsCallable() {
      UnaryCallable<MutateRowsRequest, Void> baseCallable = createMutateRowsBaseCallable();
  
      return createUserFacingUnaryCallable(
          "BulkMutateRows", new BulkMutateRowsUserFacingCallable(baseCallable, requestContext));
    }
docs: Creates a callable chain to handle MutatesRows RPCs. This is meant to be used for manual
  batching. The chain will:
  
  <ul>
  <li>Convert a {@link BulkMutation} into a {@link MutateRowsRequest}.
  <li>Process the response and schedule retries. At the end of each attempt, entries that have
  been applied, are filtered from the next attempt. Also, any entries that failed with a
  nontransient error, are filtered from the next attempt. This will continue until there
  are no more entries or there are no more retry attempts left.
  <li>Wrap batch failures in a {@link
  com.google.cloud.bigtable.data.v2.models.MutateRowsException}.
  </ul>