We introduced a Java Security Manager in v8.0. With a Security Manager installed, Java is caches positive DNS resolutions forever instead of a finite amount of time (30s in the implementations we've checked.)
Services like devops platforms often regularly change IP addresses, so if SonarQube is not able to expire DNS cache entries, it will fail to connect to them once the IP address changes.
We should explicitly set the DNS cache TTL to 30s for the Compute Engine process, where the security manager is currently used.
It will only be done if it's not already set through a java security properties file, so users can still configure it for the JVM.