The class AbstractParsingIssueStrategy uses:

ChangeLogSet changeSets = build.getChangeSet();

The class that represents the ChangeLogSet is:

ChangeLogSet class: class hudson.plugins.git.GitChangeSetList

which is output in the build.

In the GitChangeSet class getMsg returns the title or the first line of the commit 

@Exported
public String getMsg() {
 return this.title;
}

Which is what is used in MentionedInCommitStrategy:

@Override
public List<JiraCommit> getJiraIssuesFromChangeSet(final ChangeLogSet.Entry change)
{
 final List<JiraCommit> result = new ArrayList<>();
 final List<String> foundTickets = new ArrayList<>();

 for (String validJiraPrefix : Config.getGlobalConfig().getJiraTickets())
 {
 String msg = change.getMsg();
...

The problem is our git commit standards specify having the JIRA at the end, for example:

Upgraded Docker Image
See JAS-1234

so what is getting passed is the first line, and the mentionedInCommitStrategy does not pick up any JIRA.

Perhaps if the ChangeLogSet.Entry class in jenkins cored exposed getComment this could be used instead in mentionedInCommitStrategy.