When trying to serialize a Git Changeset (a property of my plugin's 'MantisCarryOverChangeSetAction'), resulting from saving an 'Action' using build.addAction(), the following error is seen.  The code would be in GitChangeset.java, the DateTimeFormatter calls:

Refusing to marshal java.time.format.DateTimeFormatter for security reasons; see https://jenkins.io/redirect/class-filter/

Stack trace attached