Accessing custom fields of issue in Custom attachment callback

[Siavosh Kasravi]

I want to attach a file to my custom email. The file is attached to the issue but its name is equal to one of issue custom fields.

I am using "Send a custom email" option of Adaptavist ScriptRunner. There you can access issue in Condition and Configuration field but not in  Custom attachment callback field.

So is there a way to fix it?