Hello! Do you still need the answer? Here is it
$connections = new VMware_VCloud_API_NetworkConnectionSectionType();
$connection = new VMware_VCloud_API_NetworkConnectionType();
$connection->setIpAddress($network->internalIp());
// Any setters from this class
$connections->addNetworkConnection($connection);
// Or collect array of connections and invoke $connections->setNetworkConnection($arrayOfConnections)
$vm->modifyNetworkConnectionSettings($connections);