public long[] getThreadIds() {
    Set<Thread> threads = getThreads();
    long[] threadIds = new long[threads.size()];

    int i = 0;
    for (Thread thread : threads) {
      threadIds[i++] = thread.getId();
    }

    return threadIds;
  }
Returns an array of {@code Thread Ids} that are directly in the {@code ExecutorService}'s
{@code ThreadGroup} excluding subgroups. {@code long[]} is returned to facilitate using JDK
APIs such as {@code ThreadMXBean#getThreadInfo(long[], int)}.

@return an array of {@code Thread Ids} that are directly in the {@code ExecutorService}'s
        {@code ThreadGroup} excluding subgroups
geode-junit/src/main/java/org/apache/geode/test/junit/rules/ExecutorServiceRule.java