refactor: Made auth_headers and auth_params of `APIAuthenticatorB…

…ase` simple instance attributes instead of decorated properties

Closes #925

singer_sdk/authenticators.py

@@ -79,7 +79,12 @@ def __call__(cls, *args: t.Any, **kwargs: t.Any) -> t.Any:  # noqa: ANN401
 
 
 class APIAuthenticatorBase:
-    """Base class for offloading API auth."""
+    """Base class for offloading API auth.
+
+    Attributes:
+        auth_headers: HTTP headers for authentication.
+        auth_params: URL query parameters for authentication.
+    """
 
     def __init__(self, stream: RESTStream) -> None:
         """Init authenticator.
@@ -89,8 +94,8 @@ def __init__(self, stream: RESTStream) -> None:
         """
         self.tap_name: str = stream.tap_name
         self._config: dict[str, t.Any] = dict(stream.config)
-        self._auth_headers: dict[str, t.Any] = {}
-        self._auth_params: dict[str, t.Any] = {}
+        self.auth_headers: dict[str, t.Any] = {}
+        self.auth_params: dict[str, t.Any] = {}
         self.logger: logging.Logger = stream.logger
 
     @property
@@ -102,24 +107,6 @@ def config(self) -> t.Mapping[str, t.Any]:
         """
         return MappingProxyType(self._config)
 
-    @property
-    def auth_headers(self) -> dict:
-        """Get headers.
-
-        Returns:
-            HTTP headers for authentication.
-        """
-        return self._auth_headers or {}
-
-    @property
-    def auth_params(self) -> dict:
-        """Get query parameters.
-
-        Returns:
-            URL query parameters for authentication.
-        """
-        return self._auth_params or {}
-
     def authenticate_request(
         self,
         request: requests.PreparedRequest,