Grails: how do I check if field-being-validated was already added to a different Domain class?

Question

I have a Domain class of NameAndAddress. Each one can be a Musician or a CommunityMember, but should not be both.

class NameAndAddress {
    ...
}

class Musician {
    NameAndAddress nameAndAddress
}

class CommunityMember {
    NameAndAddress nameAndAddress
}

I want to add a validator to both of them, checking the above rule. I start with Musician:

class Musician {
    NameAndAddress nameAndAddress

    static constraints = {
        nameAndAddress(validator: { thisField ->
            return (CommunityMember.findByNameAndAddress(thisField) == null) ? true : false
        })
    }
}

When I run validate() on a Musician though I get:

groovy.lang.MissingMethodException: No signature of method: CommunityMember.findByNameAndAddress() is applicable for argument types: (NameAndAddress) values: [NameAndAddress : 1]
Possible solutions: findByNameAndAddress([Ljava.lang.Object;)

I don't understand the error. Isn't it saying a NameAndAddress object is invalid to give to something expecting... a NameAndAddress object??

What do I do to get this working?

---

Edit:
(workaround)- Still not working using above method. I have a ugly workaround that @sudhir pointed out gives a performance hit. This code DOES work though, if it helps people understand what I'm trying to do in a cleaner way:

nameAndAddress(validator: { thisField, thisObject ->
    boolean notACommunityMember = true

    for (CommunityMember communityMember : CommunityMember.list()) {
        if (communityMember.getNameAndAddress().getId() == thisField.getId()) {
            notACommunityMember = false
            break
        }
    }

    return notACommunityMember
})

---

Edit2:
(The unit test code calling validate, requested by comments)-

@TestMixin(DomainClassUnitTestMixin)
class MusicianTest ...

    NameAndAddress aNameAndAddress = new NameAndAddress()

    mockDomain(CommunityMember, [
        [nameAndAddress: aNameAndAddress]
    ])

    Musician musician = new Musician(nameAndAddress: aNameAndAddress)

    musician.validate()
    assert musician.errors["nameAndAddress"] != null

Answer 1

Answered by Sudhir in the comments. Having "And" (or, assumingly, any predicate) in the a Domain class name will screw up Grails' odd little findByThenPutVariablesInTheMethodName syntax

Renamed class to NameAddress, and everything went great.

As an extra heads up to anyone doing this, be sure to use Grails' mockDomain class when doing a unit test that involves DomainClass.findByWhatever. I put my example at the very bottom of the question