Is this not possible or am I doing it wrong?

I want a native method of a class to create an instance of an inner class.

/* A  class with an inner class */
public final class A {

   public B method_X() {
       ...
       return new B(y, p, o);
   }

   public B method_Y() {
       ...
       return native_I(...)
   }

   private native B native_I(...);

   public final class B {
       // some members
       private B(String y, int p, boolean o) {
           ....
       }
   }
}

JNIEXPORT ....native_I(JNIEnv *env, jobject obj, ...) {
  ...
  jclass cls = (*env)->FindClass(env, "com/..../A.B);
  jmethodid mid = (*env)->GetMethodID(env, cls, "<init>",
"(Ljava/lang/String;IZ)V");
  ...
}

The FindClass is throwing NoClassDefFoundError

Is that
a. because it cannot handle inner classes
b. because I have written the name wrong
c. I don't know what I am talking about
d. ...

TIA