It's already in qt5.14

resources/ews/test/statemonitor.h

@@ -57,13 +57,7 @@ template<typename T>
 CollectionStateMonitor<T>::CollectionStateMonitor(QObject *parent, const QHash<QString, T> &stateHash, const QString &inboxId, const StateComparisonFunc &comparisonFunc, int recheckInterval)
     : StateMonitorBase(parent)
     , mMonitor(this)
-#if QT_VERSION < QT_VERSION_CHECK(5 \
-                                  , 14 \
-                                  , 0)
-    , mPending(stateHash.keys().toSet())
-#else
     , mPending(stateHash.keyBegin(), stateHash.keyEnd())
-#endif
     , mStateHash(stateHash)
     , mComparisonFunc(comparisonFunc)
     , mInboxId(inboxId)

resources/openxchange/openxchangeresource.cpp

@@ -96,11 +96,7 @@ private:
     template<typename T>
     static inline RemoteInformation loadImpl(const T &entity)
     {
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
-        const QStringList parts = entity.remoteRevision().split(QLatin1Char(':'), QString::KeepEmptyParts);
-#else
         const QStringList parts = entity.remoteRevision().split(QLatin1Char(':'), Qt::KeepEmptyParts);
-#endif
 
         OXA::Folder::Module module = OXA::Folder::Unbound;
 
@@ -161,17 +157,9 @@ public:
     ObjectsLastSync()
     {
         if (!Settings::self()->objectsLastSync().isEmpty()) {
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
-            const QStringList pairs = Settings::self()->objectsLastSync().split(QLatin1Char(':'), QString::KeepEmptyParts);
-#else
             const QStringList pairs = Settings::self()->objectsLastSync().split(QLatin1Char(':'), Qt::KeepEmptyParts);
-#endif
             for (const QString &pair : pairs) {
-#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
-                const QStringList entry = pair.split(QLatin1Char('='), QString::KeepEmptyParts);
-#else
                 const QStringList entry = pair.split(QLatin1Char('='), Qt::KeepEmptyParts);
-#endif
                 mObjectsMap.insert(entry.at(0).toLongLong(), entry.at(1).toULongLong());
             }
         }