fix: [stix2 import] Made the Observable objects fetching method available for all standalone Observable objects conversion classes

Author: chrisr3d

misp_stix_converter/stix2misp/converters/stix2_observable_objects_converter.py

@@ -35,6 +35,8 @@
 
 
 class STIX2SampleObervableParser(metaclass=ABCMeta):
+    def _fetch_observable(self, object_ref: str) -> dict:
+        return self.main_parser._observable[object_ref]
 
     def _parse_artifact_observable_object(
             self, artifact_ref: str, *args) -> MISPObject:
@@ -235,9 +237,6 @@ def _create_misp_object_from_observable(
         )
         return misp_object
 
-    def _fetch_observable(self, object_ref: str) -> dict:
-        return self.main_parser._observable[object_ref]
-
     def _parse_as_observable_object(self, as_ref: str) -> _MISP_CONTENT_TYPING:
         observable = self._fetch_observable(as_ref)
         if observable['used'].get(self.event_uuid, False):