code: private static <R> RowKey buildRowKey(AssociationKey associationKey, R row, AssociationRowAccessor<R> accessor) {
  		String[] columnNames = associationKey.getMetadata().getRowKeyColumnNames();
  		Object[] columnValues = new Object[columnNames.length];
  
  		for ( int i = 0; i < columnNames.length; i++ ) {
  			String columnName = columnNames[i];
  			columnValues[i] = associationKey.getMetadata().isKeyColumn( columnName ) ? associationKey.getColumnValue( columnName ) : accessor.get( row, columnName );
  		}
  
  		return new RowKey( columnNames, columnValues );
  	}
docs: Creates the row key of the given association row; columns present in the given association key will be obtained
  from there, all other columns from the given native association row.