There were warning about not readable libraries but stupidly missed them because of minimizing the output panel from CMake GUI.
Anyway, build is OK but will halt a bit further while creating the jar, so I followed your suggestions here and manually did
cd Wrapping/Java/CMakeFiles/vtkjava.dir/
jar --create -f ../../../../lib/java/vtk-9.1.0.jar vtk
And then I can run Java wrapper \o/ thanks for your help and your posts about Java 