Fix passing of future handle through Java, now passes a FutureHandleId instead.
Fix passing of future handle through Java, now passes a FutureHandleId instead.

PiperOrigin-RevId: 311166882

firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk,firebase/firebase-cpp-sdk