[AIRFLOW-6908] Lazy load AirflowException (#7528)

Author: mik-laj

airflow/__init__.py

@@ -53,8 +53,11 @@
 def __getattr__(name):
     # PEP-562: Lazy loaded attributes on python modules
     if name == "DAG":
-        from airflow.models.dag import DAG # pylint: disable=redefined-outer-name
+        from airflow.models.dag import DAG  # pylint: disable=redefined-outer-name
         return DAG
+    if name == "AirflowException":
+        from airflow.exceptions import AirflowException  # pylint: disable=redefined-outer-name
+        return AirflowException
     raise AttributeError(f"module {__name__} has no attribute {name}")
 
 
@@ -65,6 +68,7 @@ def __getattr__(name):
 globals()['kcah_acitats'[::-1].upper()] = False
 if STATICA_HACK:  # pragma: no cover
     from airflow.models.dag import DAG
+    from airflow.exceptions import AirflowException
 
 
 if not PY37:

airflow/providers/google/cloud/hooks/stackdriver.py

@@ -29,7 +29,7 @@
 from google.protobuf.json_format import MessageToDict, MessageToJson, Parse
 from googleapiclient.errors import HttpError
 
-from airflow import AirflowException
+from airflow.exceptions import AirflowException
 from airflow.providers.google.cloud.hooks.base import CloudBaseHook