Backport #721 into `2.2.x` branch

[elefeint]

Issue surfaced in spring-cloud-gcp build -- using spring-cloud-bus at version 2.2.2.BUILD-SNAPSHOT and spring-cloud-commons at 2.2.3.BUILD-SNAPSHOT currently fails.

The use of the new utility got backported in spring-cloud-bus, but it does not yet exist in commons, leading to the following startup error:

java.lang.NoSuchMethodError: 'java.lang.String org.springframework.cloud.commons.util.IdUtils.getUnresolvedServiceId()'
	at org.springframework.cloud.bus.BusEnvironmentPostProcessor.postProcessEnvironment(BusEnvironmentPostProcessor.java:48)

#721 getting backported in spring-cloud-commons into 2.2.x branch would fix the issue.

[ryanjbaxter]

@elefeint #721 was merged into the 2.2.x branch and then merged forward into master

https://github.com/spring-cloud/spring-cloud-commons/blob/2.2.x/spring-cloud-commons/src/main/java/org/springframework/cloud/commons/util/IdUtils.java

[elefeint]

I see what happened -- we are still on spring-cloud-commons:2.2.1.BUILD-SNAPSHOT. I'll update the dependency.

Sorry for the noise!