Describe the bug
Artifactory plugin failing with java.lang.NullPointerException

To Reproduce
Whenever we try to upload artifacts, we face the below issue whenever we generate cloudbees jobs from Jobdsl for the first time we see this issue. And then once you reset "Override default deployer credentials" to none from Artifactory plugin parameter, and re-run the issue disappears. It's behaving weird.

Expected behavior
It has to upload artifacts to jfrog without null pointer exception even though you had over the credentials.
Note: I had already configured Artifactory plugin configuration globally in cloudbees with creds

Screenshots

Versions

• Jenkins Artifactory plugin version: 3.16.2
• Jenkins operating system: CloudBees CI Managed Controller 2.332.2.6-rolling
• Artifactory Version: Enterprise Plus 7.37.14 rev 73714900 Licensed to Acquia, Inc.

Additional context
12:04:36 FATAL: null
12:04:36 java.lang.NullPointerException
12:04:36 at org.jfrog.hudson.util.SpecUtils.getSpecStringFromSpecConf(SpecUtils.java:20)
12:04:36 at org.jfrog.hudson.generic.ArtifactoryGenericConfigurator.setUp(ArtifactoryGenericConfigurator.java:375)
12:04:36 at hudson.model.Build$BuildExecution.doRun(Build.java:158)
12:04:36 at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:522)
12:04:36 at hudson.model.Run.execute(Run.java:1896)
12:04:36 at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:44)
12:04:36 at hudson.model.ResourceController.execute(ResourceController.java:101)
12:04:36 at hudson.model.Executor.run(Executor.java:442)