@Override
  public synchronized boolean isDone() {
    return !thread.isAlive();
  }
Tests if this {@code AsyncInvocation}'s thread is alive. A thread is alive if it has been
started and has not yet died.

@return {@code true} if this {@code AsyncInvocation}'s thread is alive; {@code false}
        otherwise.
geode-dunit/src/main/java/org/apache/geode/test/dunit/AsyncInvocation.java