public final ImmutableList<TypeToken<? extends Throwable>> getExceptionTypes() {
    ImmutableList.Builder<TypeToken<? extends Throwable>> builder = ImmutableList.builder();
    for (Type type : getGenericExceptionTypes()) {
      // getGenericExceptionTypes() will never return a type that's not exception
      @SuppressWarnings("unchecked")
      TypeToken<? extends Throwable> exceptionType =