Using master (98958c81f5065a5de13699d46995d278ecb6709e) with Qt `5.12.3` (also tested with depends) with multiple wallets available. None are shown in the `Open Wallet ->` menu in the gui. The wallets can be loaded from the console, bitcoin-cli etc.
#include <qt/bitcoingui.h>
#include <qt/bitcoinunits.h>
#include <qt/clientmodel.h>
#include <qt/guiconstants.h>
#include <qt/guiutil.h>
#include <qt/modaloverlay.h>
#include <qt/networkstyle.h>
#include <qt/notificator.h>
#include <qt/openuridialog.h>
#include <qt/optionsdialog.h>
#include <qt/optionsmodel.h>
#include <qt/platformstyle.h>
#include <qt/rpcconsole.h>
#include <qt/utilitydialog.h>
#ifdef ENABLE_WALLET
#include <qt/walletcontroller.h>
#include <qt/walletframe.h>
#include <qt/walletmodel.h>
#include <qt/walletview.h>
#endif