Static Type checker reporting invalid error

public class ClassA<T> {
    <X> Class<X> foo(Class<X> classType){
        return classType;
    }
}

import groovy.transform.CompileStatic

@CompileStatic
class ClassB {
    void bar() {
        def ClassA<Long> a = new ClassA<Long>();
        a.foo(this.getClass());
    }
}