<uses-permission android:name="android.permission.MANAGE_DOCUMENTS"/>

binding.fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (ContextCompat.checkSelfPermission(getApplicationContext(),
                        Manifest.permission.MANAGE_DOCUMENTS) != PackageManager.PERMISSION_GRANTED) {

                    // Should we show an explanation?
                    if (ActivityCompat.shouldShowRequestPermissionRationale(OpenActivity.this,
                            Manifest.permission.MANAGE_DOCUMENTS)) {

                        AlertDialog.Builder builder = new AlertDialog.Builder(mContext);
                        builder.setMessage("We need permissions")
                                .setCancelable(false)
                                .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog, int id) {
                                        ActivityCompat.requestPermissions(OpenActivity.this,
                                                new String[]{Manifest.permission.MANAGE_DOCUMENTS},
                                                REQUEST_PERMISSION);
                                    }
                                });
                        AlertDialog alert = builder.create();
                        alert.show();

                    } else {

                        // No explanation needed, we can request the permission.

                        ActivityCompat.requestPermissions(OpenActivity.this,
                                new String[]{Manifest.permission.MANAGE_DOCUMENTS},
                                REQUEST_PERMISSION);
                    }

                } else {
                    mIopen.openPressed();
                }
            }
        });