code: private RealConnection findHealthyConnection(int connectTimeout, int readTimeout,
        int writeTimeout, int pingIntervalMillis, boolean connectionRetryEnabled,
        boolean doExtensiveHealthChecks) throws IOException {
      while (true) {
        RealConnection candidate = findConnection(connectTimeout, readTimeout, writeTimeout,
            pingIntervalMillis, connectionRetryEnabled);
  
        // If this is a brand new connection, we can skip the extensive health checks.
        synchronized (connectionPool) {
          if (candidate.successCount == 0) {
            return candidate;
          }
        }
  
        // Do a (potentially slow) check to confirm that the pooled connection is still good. If it
        // isn't, take it out of the pool and start again.
        if (!candidate.isHealthy(doExtensiveHealthChecks)) {
          candidate.noNewExchanges();
          continue;
        }
  
        return candidate;
      }
    }
docs: Finds a connection and returns it if it is healthy. If it is unhealthy the process is repeated
  until a healthy connection is found.