code: public void throwIfNotEmpty() {
          synchronized (nested) {
              if (nested.isEmpty()) {
                  // Do nothing
              } else if (nested.size() == 1) {
                  Throwable t = nested.get(0);
                  TigerThrower.sneakyThrow(t);
              } else {
                  throw this;
              }
          }
      }
docs: If this <code>MultiException</code> is empty then no action is taken,
  if it contains a single <code>Throwable</code> that is thrown,
  otherwise this <code>MultiException</code> is thrown.