code: public boolean addCassandraHost(CassandraHost cassandraHost) {
      if ( !getHosts().contains(cassandraHost) ) {
        HClientPool pool = null;
        try {
          cassandraHostConfigurator.applyConfig(cassandraHost);
          pool = cassandraHostConfigurator.getLoadBalancingPolicy().createConnection(clientFactory, cassandraHost, monitor);
          hostPools.putIfAbsent(cassandraHost, pool);
          log.info("Added host {} to pool", cassandraHost.getName());
          listenerHandler.fireOnAddHost(cassandraHost, true, null, null);
          return true;
        } catch (HectorTransportException hte) {
          String errorMessage = "Transport exception host to HConnectionManager: " + cassandraHost;
          log.error(errorMessage, hte);
          listenerHandler.fireOnAddHost(cassandraHost, false, errorMessage, hte);
        } catch (Exception ex) {
          String errorMessage = "General exception host to HConnectionManager: " + cassandraHost;
          log.error(errorMessage, ex);
          listenerHandler.fireOnAddHost(cassandraHost, false, errorMessage, ex);
        }
      } else {
        String message = "Host already existed for pool " + cassandraHost.getName();
        log.info(message);
        listenerHandler.fireOnAddHost(cassandraHost, false, message, null);
      }
      return false;
    }
docs: Returns true if the host was successfully added. In any sort of failure exceptions are
  caught and logged, returning false.
  @param cassandraHost
  @return