GroovyMock object on a final class doesn't work properly inside statically compiled service

Issue description

GroovyMock interactions for final class doesn't work inside@CompileStatic annotated class or in plain java class. In this case mock object will use real method implementation instead of provided interaction.

Minimal code to reproduce

import groovy.transform.CompileStatic
import spock.lang.Specification

class UserServiceSpec extends Specification {
    def "test final class mock interactions"() {
        setup:
            def mock = GroovyMock(FinalClass) {
                getName() >> "Foo Bar"
            }
        when:
            new StaticService().getName(mock)
        then:
            thrown(UnsupportedOperationException)
        expect:
            new GroovyService().getName(mock) == "FOO BAR"
    }
}

final class FinalClass {
    String getName() {
        throw new UnsupportedOperationException("Not implemented")    
    }
}

class GroovyService {
    String getName(FinalClass obj) {
        obj.name.toUpperCase()
    }
}

@CompileStatic
class StaticService {
    String getName(FinalClass obj) {
        obj.name.toUpperCase()
    }
}

Environment

Java: OpenJDK Runtime Environment (build 1.8.0_144-b01)
Gradle: 3.5

Gradle dependencies

compile 'org.codehaus.groovy:groovy-all:2.4.12'
compile 'org.spockframework:spock-core:1.1-groovy-2.4'
compile 'cglib:cglib-nodep:3.2.5'

Start with the minimal reproduction in the issue, comparing GroovyService and @CompileStatic StaticService when GroovyMock targets the final FinalClass; also check the plain Java case described. Trace the GroovyMock interaction path for the final class and verify that getName() uses the provided interaction rather than the real implementation in both statically compiled and Java callers.