public Connection useFirst() {
    Connection connection;
    while (null != (connection = connections.pollFirst())) {
      if (connection.activate()) {
        return connection;
      }
    }
    return null;
  }
Remove, activate, and return the first connection.
Connections that can not be activated will be removed from the manager but not returned.

@return the activated connection or null if none found
geode-core/src/main/java/org/apache/geode/cache/client/internal/pooling/AvailableConnectionManager.java