In many TestRail, users define custom user fields for test cases, like in this screenshot
Firefly allows users to configure custom fields easily by using a configuration wizard.
To open the wizard, simple right click on your project and select
Firefly: Configure custom fields.
Simply click on Add button (green plus icon) and specify TestRail field label, SoapUI field name and default value.
Once you click on Save button, the default values for each of the custom properties will be added to all Test Cases of ReadyAPI project.
If you re-export project to TestRail, you will see that values from custom fields are transferred into TestRail Test Case.