I have created a custom field in order to log work during workflow transition. Procedure:

• Added custom field type "Worklogger for an issue"
• Assigned custom field to the workflow transition screen
• Defined a validator during the transition to establish that time spent and comment are mandatory:

Steps to reproduce the error:
1. Create a new ticket
2. Transition the ticket until the custom field appears
3. Insert time spent and no comment
4. Submit
The application shows a message that explain that the comment field is mandatory. The time spent is resetted to zero
5. Insert time spent and comment
6. Submit

The result is that both the submittions have been recorded instead of record just the last one.