code: @InternalApi
    public CheckAndMutateRowRequest toProto(RequestContext requestContext) {
      Preconditions.checkState(
          !builder.getTrueMutationsList().isEmpty() || !builder.getFalseMutationsList().isEmpty(),
          "ConditionalRowMutations must have `then` or `otherwise` mutations.");
      String tableName =
          NameUtil.formatTableName(
              requestContext.getProjectId(), requestContext.getInstanceId(), tableId);
      return builder
          .setTableName(tableName.toString())
          .setAppProfileId(requestContext.getAppProfileId())
          .build();
    }
docs: Creates the underlying {@link CheckAndMutateRowRequest} protobuf.
  
  <p>This method is considered an internal implementation detail and not meant to be used by
  applications.