Email validator not allowing subdomains for external subjects

A few API tests are failing after a recent patch (GRP-1652, 2.3.0 UI patch 40). . The commons validator can check for local and subdomain addresses, but doesn't by default.

testNonDynamicDescription(edu.internet2.middleware.grouper.externalSubjects.ExternalSubjectTest)java.lang.RuntimeException: Not allowed to register this identifier, should be something like a@b.c: 'a@idp.b.c'
    at edu.internet2.middleware.grouper.externalSubjects.ExternalSubject.validateIdentifier(ExternalSubject.java:1009)
    at edu.internet2.middleware.grouper.externalSubjects.ExternalSubject.store(ExternalSubject.java:897)
    at edu.internet2.middleware.grouper.externalSubjects.ExternalSubject.store(ExternalSubject.java:776)
    at edu.internet2.middleware.grouper.externalSubjects.ExternalSubjectTest.testNonDynamicDescription(ExternalSubjectTest.java:677)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at edu.internet2.middleware.grouper.AllTests.main(AllTests.java:160)