lint: tidy up code some more, pylint is enforcing

app/models/mirrors.py

@@ -1,6 +1,5 @@
 from typing import Optional, List
 
-from flask import current_app
 from tldextract import extract
 
 from app.brm.brn import BRN
@@ -20,8 +19,14 @@ class Origin(AbstractConfiguration):
     proxies = db.relationship("Proxy", back_populates="origin")
 
     @property
-    def brn(self) -> str:
-        return f"brn:{current_app.config['GLOBAL_NAMESPACE']}:{self.group_id}:mirror:conf:origin/{self.domain_name}"
+    def brn(self) -> BRN:
+        return BRN(
+            group_id=self.group_id,
+            product="mirror",
+            provider="conf",
+            resource_type="origin",
+            resource_id="self.domain_name"
+        )
 
     @classmethod
     def csv_header(cls) -> List[str]: