// The expression is a validator specification, such as "required,minLength=5".
// ValidatorBindingFactory is the odd man out becasuse it needs the binding component (the
// component whose parameter is to be bound) rather than the containing component, the way
// most factories work.
FieldValidator validator = fieldValidatorSource.createValidators(field, expression);
return new LiteralBinding(description, validator, location);
}