why android.view.ActionMode.Callback has two of each member methods?

Question

I hope you are well.

My question is why this callback class has two of the same functions?

the only difference that I see is that some functions deal with nullable and the others don't, but in the end, we can achieve what want with both ways (with nullable or without nullable)

if anyone has a good explanation for this and thanks in advance

private val actionModeCallback = object : Callback, android.view.ActionMode.Callback {
        override fun onCreateActionMode(mode: ActionMode, menu: Menu): Boolean {
            return false
        }

        // Called each time the action mode is shown. Always called after onCreateActionMode, but
        // may be called multiple times if the mode is invalidated.
        override fun onPrepareActionMode(mode: ActionMode, menu: Menu): Boolean {
            return false // Return false if nothing is done
        }

        // Called when the user selects a contextual menu item
        override fun onActionItemClicked(mode: ActionMode, item: MenuItem): Boolean {
            return false
        }

        // Called when the user exits the action mode
        override fun onDestroyActionMode(mode: ActionMode) {
           
            actionMode = null
        }

        override fun onCreateActionMode(p0: android.view.ActionMode?, p1: Menu?): Boolean {
            // Called when the action mode is created; startActionMode() was called
            // Inflate a menu resource providing context menu items
            val inflater: MenuInflater = p0!!.menuInflater
            inflater.inflate(R.menu.memory_fragment_context_menu, p1)
            return true
        }

        override fun onPrepareActionMode(p0: android.view.ActionMode?, p1: Menu?): Boolean {
            return false
        }

        override fun onActionItemClicked(p0: android.view.ActionMode?, p1: MenuItem?): Boolean {
            return when (p1?.itemId) {
                R.id.someId -> {
                    Toast.makeText(context,"go to hell", Toast.LENGTH_LONG).show()
                    selectionTracker?.clearSelection()
                    p0?.finish() // Action picked, so close the CAB
                    true
                }
                else -> false
            }
        }

        override fun onDestroyActionMode(p0: android.view.ActionMode?) {
            
        }
    }