Well, https://mavenrepo.openmrs.org/nexus/content/repositories/public/com/atlassian/jira/jira-rest-java-client/2.0.0-m2/jira-rest-java-client-2.0.0-m2.jar seems to work fine. So it doesn’t seem that the Jfrog repository has any problem.
Now, what’s the version of the JDK that is running your maven? What’s your maven version? It’s known that older versions of the JDK do not like the letsencrypt certificate, and older versions of maven do not do the redirect to https.