code: public static boolean shouldStub(CtMethod method, Collection<Class<?>> classesToStub) {
      // Stub any methods for which we have given explicit implementations
      if (STUB_METHODS.containsKey(new ClassAndMethod(
          method.getDeclaringClass().getName(), method.getName()))) {
        return true;
      }
  
      // Stub all non-abstract methods of classes for which stubbing has been requested
      for (Class<?> clazz : classesToStub) {
        if (declaringClassIs(method, clazz) && (method.getModifiers() & Modifier.ABSTRACT) == 0) {
          return true;
        }
      }
  
      // Stub all native methods
      if ((method.getModifiers() & Modifier.NATIVE) != 0) {
        return true;
      }
  
      return false;
    }
docs: Returns whether the behavior of the given method should be replaced.