After installing Omnet++ 5.3 in ubuntu 18.04 LTS, I imported INET 3.99.3 project folder and I was not able to build from IDE. Later I found an article and resolved building issues.
But now, I am facing an issue to run examples, are located in INET 3.99.3 project folder as shown in below:
Error: Cannot load library '../../../src//libINET.so': ../../../src//libINET.so: undefined symbol: _ZTIN3osg5GroupE