try subclassing instead of protocol

dsp_permissions_scripts/doap/doap_model.py

@@ -1,9 +1,9 @@
 from __future__ import annotations
 
-from typing import Protocol
 from typing import Self
 
 from pydantic import BaseModel
+from pydantic import ConfigDict
 from pydantic import model_validator
 
 from dsp_permissions_scripts.models.group import Group
@@ -13,12 +13,14 @@
 class Doap(BaseModel):
     """Model representing a DOAP, containing the target, the scope and the IRI of the DOAP."""
 
+    model_config = ConfigDict(arbitrary_types_allowed=True)
+
     target: DoapTarget
     scope: PermissionScope
     doap_iri: str
 
 
-class DoapTarget(Protocol):
+class DoapTarget:
     """
     A DOAP can be defined for either a Group, or for a ResourceClass, or for a Property,
     or for a combination of ResourceClass and Property.
@@ -28,12 +30,12 @@ class DoapTarget(Protocol):
     project_iri: str
 
 
-class GroupDoapTarget(BaseModel):
+class GroupDoapTarget(BaseModel, DoapTarget):
     project_iri: str
     group: Group
 
 
-class EntityDoapTarget(BaseModel):
+class EntityDoapTarget(BaseModel, DoapTarget):
     project_iri: str
     resource_class: str | None = None
     property: str | None = None