private int addContentHash(final PropertyKey key, final int contentHash) {

		final Object value = getProperty(key);
		if (value != null) {

			return contentHash ^ value.hashCode();
		}

		return contentHash;
	}
private int addContentHash ( final PropertyKey key , final int contentHash ) { final Object value = getProperty ( key ) ; if ( value != null ) { return contentHash ^ value . hashCode ( ) ; } return contentHash ; }
----- private methods -----