code: private EntityKey getEntityKey(AssociationKey associationKey, RowKey rowKey) {
  		String[] associationKeyColumns = associationKey.getMetadata().getAssociatedEntityKeyMetadata().getAssociationKeyColumns();
  		Object[] columnValues = new Object[associationKeyColumns.length];
  		int i = 0;
  
  		for ( String associationKeyColumn : associationKeyColumns ) {
  			columnValues[i] = rowKey.getColumnValue( associationKeyColumn );
  			i++;
  		}
  
  		EntityKeyMetadata entityKeyMetadata = associationKey.getMetadata().getAssociatedEntityKeyMetadata().getEntityKeyMetadata();
  		return new EntityKey( entityKeyMetadata, columnValues );
  	}
docs: Returns the entity key on the other side of association row represented by the given row key.
  <p>
  <b>Note:</b> May only be invoked if the row key actually contains all the columns making up that entity key.
  Specifically, it may <b>not</b> be invoked if the association has index columns (maps, ordered collections), as
  the entity key columns will not be part of the row key in this case.