@Override
  public VM getVM(String geodeVersion, int whichVM) {
    return getVM(VmConfiguration.forGeodeVersion(geodeVersion), whichVM);
  }
Retrieves one of this host's VMs based on the specified VM ID. This will not bounce VM to a
different version. It will only get the current running VM or launch a new one if not already
launched.

@param n ID of the requested VM; a value of <code>-1</code> will return the controller VM,
       which may be useful for debugging.
@return VM for the requested VM ID.
geode-dunit/src/main/java/org/apache/geode/test/dunit/internal/DUnitHost.java