public AtomicInteger reference(final Serializable id) {
    return counters.get(id);
  }
Returns the {@code AtomicInteger} identified by the specified {@code id}.

@param id the id of the {@code AtomicInteger}
@return the {@code AtomicInteger}
geode-dunit/src/main/java/org/apache/geode/test/dunit/rules/DistributedCounters.java