docs: @Override
  	public String getSingleRowKeyColumnNotContainedInAssociationKey() {
  		String nonKeyColumn = null;
  
  		for ( String column : getRowKeyColumnNames() ) {
  			if ( !isKeyColumn( column ) ) {
  				if ( nonKeyColumn != null ) {
  					// more than one column which is not contained in the association key; thus rows of this
  					// association will be represented by DBObjects rather than single String, int etc. objects
  					return null;
  				}
  				else {
  					nonKeyColumn = column;
  				}
  			}
  		}
  
  		return nonKeyColumn;
  	}