You would be much better and easier bumping jenkins.version to 2.60.1, since this is the first LTS where Jenkins is using Java 8.
Basically, if you release your plugin using a baseline <2.60, and your plugin is compiled for Java 8, then any user of your plugin who upgrades, and uses Jenkins < 2.60 will see it blow up (hopefully, only your plugin will not be loaded, and not the whole instance screwed, but not sure, didn't check recently).
Also: if you wish to do that, please do not hesitate to file your ongoing work as a PR, and explaining what possibly is blocking you. It's *much* easier for everyone here to help you fix a given PR, than try and guess all the reasons something might be failing for.
Though, building locally:and building locally, it failed. It looks to me there is some dependency for this plugin that is not publicly accessible.
Note that we do not host non open source plugins.
Is that com.hp.sv:SVConfigurator:jar:4.20.0.49985 artifact published somewhere?
[...] Downloaded: https://redacted/content/groups/staged/org/jenkins-ci/main/jenkins-war/1.642.4/jenkins-war-1.642.4.war (64 MB at 653 kB/s)
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 02:35 min
[INFO] Finished at: 2018-06-04T10:53:34+02:00
[INFO] Final Memory: 44M/465M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal on project hp-application-automation-tools-plugin: Could not resolve dependencies for project org.jenkins-ci.plugins:hp-application-automation-tools-plugin:hpi:5.4.1-SNAPSHOT: Could not find artifact com.hp
.sv:SVConfigurator:jar:4.20.0.49985 in cloudbees-internal (https://nexus-internal.cloudbees.com/content/groups/staged/) -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
Thanks!