This callback is used for User Management operations, such as sending emails or password reset forms.
This methods which use this callback do not provide any return values, instead they either "ran" or "didn't run".
void onSuccess(java.lang.Void result)
Method invoked when a user operation completes.
Void because there is no usable return value.
void onFailure(java.lang.Throwable error)
Method invoked when a user operation fails to complete.
details about the error.