When passing a mutable instance into a method which makes a deep copy of the instance, it results in discrepancies between the forked instances. It is prone to errors if one expects the state change on the original instance to be reflected on the method with its forked instance.

Location location = new Location("gps");
Bundle bundle = new Bundle();
bundle.putFloat("someFloat", 12.3f);
location.setExtras(bundle);

// Now add more things to the bundle, but it won't modify the internal
// representation stored by Location.
bundle.putInt("someInt", 7);

private static Bundle getLocationExtras(Location location) {
  Bundle bundle = location.getExtras();
  if (bundle != null) {
    return bundle;
  }
  bundle = new Bundle();
  location.setExtras(bundle);

  // Now leaks the bundle which is subject to modification in its
  // method of invocation.
  return bundle;
}