NoncancelableBottomSheetDialogFragment.java

@Override
public void setCancelable(boolean cancelable) {
    final Dialog dialog = getDialog();
    View touchOutsideView = dialog.getWindow().getDecorView().findViewById(android.support.design.R.id.touch_outside);
    View bottomSheetView = dialog.getWindow().getDecorView().findViewById(android.support.design.R.id.design_bottom_sheet);

    if (cancelable) {
        touchOutsideView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (dialog.isShowing()) {
                    dialog.cancel();
                }
            }
        });
        BottomSheetBehavior.from(bottomSheetView).setHideable(true);
    } else {
        touchOutsideView.setOnClickListener(null);
        BottomSheetBehavior.from(bottomSheetView).setHideable(false);
    }
}