docs: public static synchronized void releaseHelper() {
  		instanceCount--;
  		logger.trace("releasing helper {}, instance count = {}", helper, instanceCount);
  		if (instanceCount <= 0) {
  			if (helper != null) {
  				logger.trace("zero instances, closing helper {}", helper);
  				helper.close();
  				helper = null;
  				wasClosed = true;
  			}
  			if (instanceCount < 0) {
  				logger.error("too many calls to release helper, instance count = {}", instanceCount);
  			}
  		}
  	}