code: public Object getColumnValue(String columnName) {
  		for ( int i = 0; i < getColumnNames().length; i++ ) {
  			String name = getColumnNames()[i];
  			if ( name.equals( columnName ) ) {
  				return getColumnValues()[i];
  			}
  		}
  
  		throw new AssertionFailure(
  				String.format( "Given column %s is not part of this key: %s", columnName, this.toString() )
  		);
  	}
docs: Returns the value of the given column if part of this key. Use {@link AssociationKeyMetadata#isKeyColumn(String)}
  to check whether a given column is part of this key prior to invoking this method.
  
  @param columnName the name of interest
  @return the value of the given column.