<p> A call to <code>notify()</code> or <code>notifyAll()</code>
  was made without any (apparent) accompanying
  modification to mutable object state.&nbsp; In general, calling a notify
  method on a monitor is done because some condition another thread is
  waiting for has become true.&nbsp; However, for the condition to be meaningful,
  it must involve a heap object that is visible to both threads.</p>

  <p> This bug does not necessarily indicate an error, since the change to
  mutable object state may have taken place in a method which then called
  the method containing the notification.</p>