code: @SafeVarargs
    public final TableBuilder columns(String... columns) {
      if (columns == null || columns.length == 0) {
        throw new InvalidOperationException("Columns array is null or empty.");
      }
      if (tableColumns != null) {
        throw new InvalidOperationException("The table columns are already defined.");
      }
      tableColumns = columns.clone();
      return this;
    }
docs: Set columns.
  @param columns Columns for the table.
  @return The builder instance for chained calls.