code: public static @NonNull Throwable unwrap(final @NonNull Throwable throwable) {
      if(throwable instanceof InvocationTargetException) {
        final /* @Nullable */ Throwable cause = throwable.getCause();
        if(cause != null) {
          return cause;
        }
      }
      return throwable;
    }
docs: Unwraps a throwable.
  
  @param throwable the throwable
  @return the unwrapped throwable, or the original throwable