QAbstractSocket上连接主机时 UnsupportedSocketOperationError抛出QSslSocket::connectToHostEncrypted()，
Environnement：Qt 5.9.3 Ubuntu 16.04（虚拟机）也Qt 5.9.3 Fedora 26（原生）
_socket = new QSslSocket{this};
connect(_socket, static_cast<void(QAbstractSocket::*) QAbstractSocket::SocketError) (&QAbstractSocket::error), this, &EventResource::streamError);
_socket->connectToHostEncrypted(_device->addressUrl().host(), 443, QSslSocket::ReadWrite, QSslSocket::IPv4Protocol);
void EventResource::streamError(QAbstractSocket::SocketError error)
{
QDebug() << "Event error: " << error;
//QAbstractSocket::UnsupportedSocketOperationError
}