then:
        thrown(ManifestException)

        when:
        attributes.putAll((null): 'someValue')

        then:
        thrown(ManifestException)
    }

    def testValueValidationWithPut() {
        when:
        attributes.put('key', null)

        then:
        thrown(ManifestException)
    }

    def testValueValidationWithPutAll() {
        when: