Wrong version check when syncing workflows

Steps to reproduce

1. Start a Jira 7.13.x instance and create a synchronization

2. Configure workflows to be synchronized

   1. Do not add a resolution field mapping

   2. Do not add the resolution field to the transition screen of the second side's workflow

3. Start the sync

4. Synchronize an issue and move it to a status with a resolution

Expected result

The issue is synchronized without problems.

Actual result

Jira throws an error because Backbone also tries to set the resolution when transitioning the issue.