creating a plugin with CMake

Hello list

In my software package I have a main program with - for specific tasks - plugins. Plugins are selected by
the user by clicking on a name. On selection, the plugin is loaded, connections are made and the processing
starts

Up until now I created the program(s) with qmake, there are many requests (well, at least a few) of using either
the Gnu autotools or CMake, si I started learning CMake.
find_package (Qt5Widgets REQUIRED)
find_package (Qt5Declarative REQUIRED)

Finding Qt5 as such - and even qwt that I am using - is managed, the internet gives many examples.
The make process for the main program therefore was easily(?) done.

For the plugins however I am lost. In the project files I am using for the plugins I specify "CONFIG += plugin"
I do not see a counterpart in the CMake environment. When not specifying anything like that, the cmake will create a makefile
that, when called, will create a shared object with the right names and dependencies (afaik). However, the main program refuses
to accept the plugin saying "
loading plugin for /usr/shared/sdr-j-development/linux-bin/input-plugins-sw/libdevice_cardReader.so failed
error = Plugin verification data mismatch in '/usr/shared/sdr-j-development/linux-bin/input-plugins-sw/libdevice_cardReader.so

(cardReader is here the plugin). When I run the qmake-qt5/make sequence I get a valid plugin

What should I specify additionally in the CMakeList.txt file next to
find_package (Qt5Widgets REQUIRED)
find_package (Qt5Declarative REQUIRED)


help appreciated

best
jan
ps I am working under Linux (Fedora, but the same happens when using ubuntu)