Basic implementation.
The tested operation is equality, unless it is explicitly set.
author: Rob van Maris version: $Id: BasicCompareFieldsConstraint.java,v 1.7 2006/10/16 12:56:57 pierre Exp $ since: MMBase-1.7
Constructor.
Parameters: field1 - The associated field. Parameters: field2 - The second associated field. throws: IllegalArgumentException - when an invalid argument is supplied.