Narrowing down the cause: I think it's due to the .exec file for Integration test. To proove it: I passed UT exex file to both reportsPaths in Sonar variables i.e. the following and SonarQube picked both UT/IT test coverage. This prooves that if .exec file for IT tests is good (which I think it's But I need to double check) then Sonar will pick the .exec file and show a valid coverage % instead of 0.0%. Note: the following is just to proove if Sonar is picking the values or not. itReportPath variable should use the .exe file which is generated by Integration tests by Jacoco.
sonar.jacoco.reportPath=build/jacoco/test.exec
# Sonar Integration Test Report Path
#sonar.jacoco.itReportPath=build/jacoco/testintegrationTest.exec
sonar.jacoco.itReportPath=build/jacoco/test.exec
OK Found the issue. I was running integrationTest task in Gradle and was NOT attaching the jacocoagent.jar (as per Jacoco documentation) to the target JVM (Tomcat's instance) scope. Once I did that, I removed jacoco { ... } section from integrationTest task in Gradle (build.gradle or GRADLE_HOME/init.d/some.common.gradle file as this attach jacoco agent to the Java JVM in which Gradle is running). Now, once jacocoagent.jar was attached to Tomcat's JVM (as per the line below which I added in Tomcat's startup.sh script and added the variable to the command which starts Tomcat), then I ran Gradle (integrationTest) task for running IT tests.
PROJ_EXTRA_JVM_OPTS=-javaagent:tomcat/jacocoagent.jar=destfile=build/jacoco/IT/jacocoIT.exec,append=false
Then while Gradle was in progress, tests ran and I got a file (jacocoIT.exec at the given location) with some file size BUT this is not yet the final one. I had to stop the Tomcat session/JVM instance by running Tomcat's stop.sh script. Once Tomcat was stopped, I saw jacocoIT.exec file size increased significantly and this was the valid final jacocoIT.exec file (which I needed for sonarRunner Gradle task OR sonar-runner exectuable to pick and successfully push IT code coverage data to project's sonar dashboard). Once done, I got both UT + IT and it's combined code coverage.
sonar.jacoco.reportPath=build/jacoco/UT/jacocoUT.exec
sonar.jacoco.itReportPath=build/jacoco/IT/jacocoIT.exec