Memory Leak Causing Sonar to Come down immediately after Start Up

Sonarqube 5.6 (will be upgrading to 6.7.7 and then 7.9 in the next couple of months).
Running on RHEL 6.9
java version: 1.8.0_20

Occasionally, when starting SonarQube we encounter these messages (not: the thread name is not always the same) and the application goes down shortly after start up:

2019.09.21 15:56:57 WARN web[o.a.c.l.WebappClassLoaderBase] The web application [ROOT] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.lang.Object.wait(Native Method)/

I am reluctant to attach the sonar.log because this is a public forum and it would take me quite some time to mask the proprietary information due to it’s length.

Any help you can provide to mitigate this will be greatly appreciated.

I’m afraid it only makes sense to investigate the issue if it replicates on latest LTS.

I am facing the same issue. Is any one got the answer? Help would be highly appreciated.