TopLevelItemDescriptor is the Descriptor for TopLevelItem's, generating the overview of entries at yourJenkins/newJob.

This view doesn't support loading Jenkins symbols yet, #getIconClassName() loads the job icon from a path.

It would be nice if we could make use of the common symbol syntax, like symbol-jenkins plugin-ionicons-api, to load a custom symbol for a custom job via #getIconClassName(), rather than relying on a static path.

Resources:
TopLevelItemDescriptor: https://github.com/jenkinsci/jenkins/blob/master/core/src/main/java/hudson/model/TopLevelItemDescriptor.java