I am getting unknown memory leak whenever I am closing any fragment

Question

I am making blog app and getting memory leak when ever I closing any fragment....I try to find answer and some says to null out your views reference on onDestroyView or onDestroy(I tried it both and it don't work) and than I just created blank fragment without any views(just a blue background ) and even if I am closing BlankFragment,still I am getting same memory leak...follow is the code I am using to add blank fragment

 Fragment blankFragment = new BlankFragment();
 FragmentTransaction transaction = getActivity().getSupportFragmentManager().beginTransaction();
 transaction.hide(userProfileFragment);     //hiding userProfileFragment which is current fragment
 transaction.add(R.id.frame_container, blankFragment,"blank");
 transaction.addToBackStack(null);
 transaction.commit();

and after I am closing just even a blankFragment which does not hold any views..I am getting the following memory leak warning in Leak Canary

┬───
│ GC Root: System class
│
├─ leakcanary.internal.InternalLeakCanary class
│    Leaking: NO (MainActivity↓ is not leaking and a class is never leaking)
│    ↓ static InternalLeakCanary.resumedActivity
├─ MainActivity instance
│    Leaking: NO (HomeFragment↓ is not leaking and Activity#mDestroyed is false)
│    ↓ MainActivity.startingFragment
├─ HomeFragment instance
│    Leaking: NO (UserProfile_Fragment↓ is not leaking and Fragment#mFragmentManager is not        null)
│    Fragment.mTag=home
│    ↓ HomeFragment.mFragmentManager
├─ androidx.fragment.app.FragmentManagerImpl instance
│    Leaking: NO (UserProfile_Fragment↓ is not leaking)
│    ↓ FragmentManagerImpl.mAdded
├─ java.util.ArrayList instance
│    Leaking: NO (UserProfile_Fragment↓ is not leaking)
│    ↓ ArrayList.elementData
├─ java.lang.Object[] array
│    Leaking: NO (UserProfile_Fragment↓ is not leaking)
│    ↓ Object[].[3]
├─ UserProfile_Fragment instance
│    Leaking: NO (Fragment#mFragmentManager is not null)
│    Fragment.mTag=user
│    ↓ UserProfile_Fragment.transaction
│                           ~~~~~~~~~~~
├─ androidx.fragment.app.BackStackRecord instance
│    Leaking: UNKNOWN
│    ↓ BackStackRecord.mOps
│                      ~~~~
├─ java.util.ArrayList instance
│    Leaking: UNKNOWN
│    ↓ ArrayList.elementData
│                ~~~~~~~~~~~
├─ java.lang.Object[] array
│    Leaking: UNKNOWN
│    ↓ Object[].[1]
│               ~~~
├─ androidx.fragment.app.FragmentTransaction$Op instance
│    Leaking: UNKNOWN
│    ↓ FragmentTransaction$Op.mFragment
│                             ~~~~~~~~~
╰→ BlankFragment instance Leaking: YES (ObjectWatcher was watching this because BlankFragment   received Fragment#onDestroy() callback and Fragment#mFragmentManager is null)

Answer 1

UserProfile_Fragment.transaction is the likely cause of the leak, you shouldn't hold the fragment transaction in memory as it keeps the BlankFragment.