code: public JComponent createButtonBar(final ColumnSpec columnSpec, final RowSpec rowSpec) {
  		return createButtonBar(columnSpec, rowSpec, null);
  	}
docs: Create a button bar with buttons for all the commands in this.
  
  @param columnSpec Custom columnSpec for each column containing a button,
  can be <code>null</code>.
  @param rowSpec Custom rowspec for the buttonbar, can be <code>null</code>.
  @return never null