private fun furtherProcessing(fav: HashMap<String, FavGymFirestore>, ratings: HashMap<String, GymRatingStats>, gymList: GymList, activity: Activity): Unit
Further filtering done when we retrieved data from Firebase Firestore DB such as reviews and favourite counts
fav - HashMap<String, FavGymFirestore> HashMap containing favourites per gym, stored in FavGymFirestore
ratings - HashMap<String, GymRatingStats> HashMap containing gym ratings per gym, stored in GymRatingStats
gymList - GymList Object containing all the gyms that are available and found in the dataset
activity - Activity The current activity reference for context usage