@Override
  public void close(boolean keepAlive) {
    close("Normal disconnect", null, keepAlive, false, false);
  }
Close the distributed system, cache servers, and gateways. Clears the rootRegions and
partitionedRegions map. Marks the cache as closed.

@see SystemFailure#emergencyClose()
geode-core/src/main/java/org/apache/geode/internal/cache/GemFireCacheImpl.java