private static boolean matrixEquals(@Nullable Matrix a, @Nullable Matrix b) {
    if (a == null && b == null) {
      return true;
    }
    if (a == null || b == null) {
      return false;
    }

    return a.equals(b);
  }
Nullsafe Matrix equality check. This is needed because Matrix.equals() is not nullsafe.
drawee/src/main/java/com/facebook/drawee/drawable/RoundedDrawable.java