public String equivalence(final Namespace sourceNamespace,
final String sourceValue, final Namespace targetNamespace)
throws EquivalencerException {
if (sourceNamespace == null) {
throw new InvalidArgument("sourceNamespace", sourceNamespace);
}
if (noLength(sourceValue)) {
throw new InvalidArgument("sourceValue", sourceValue);
}
if (targetNamespace == null) {
throw new InvalidArgument("targetNamespace", targetNamespace);
}
loadEquivalencingEngine();
// convert namespace and value to parameter (common model).