QHttpServerRequest doesnt compile whith DELETE

I built the files of QHttpServer with mingw and Qt 5.15 which worked well and runs like a charme in an example test project.

After including the files in my main project I got an error in QHttpServerRequest: 

qthttpserver/qthttpserver/src/httpserver/qhttpserverrequest.h:75:9: error: expected identifier before '(' token
         DELETE  = Delete,
         ^~~~~~

After deleting the uppercase DELTE in line 75 there is no error message anymore.