2 files changed, 20 insertions, 10 deletions

diff --git a/git/objects/submodule/base.py b/git/objects/submodule/base.py
index 8cf4dd1e..cbf6cd0d 100644
--- a/git/objects/submodule/base.py
+++ b/git/objects/submodule/base.py
@@ -3,7 +3,6 @@ from io import BytesIO
 import logging
 import os
 import stat
-from typing import List
 from unittest import SkipTest
 import uuid
 
@@ -27,12 +26,13 @@ from git.exc import (
 from git.objects.base import IndexObject, Object
 from git.objects.util import Traversable
 from git.util import (
-    Iterable,
+    IterableObj,
     join_path_native,
     to_native_path_linux,
     RemoteProgress,
     rmtree,
-    unbare_repo
+    unbare_repo,
+    IterableList
 )
 from git.util import HIDE_WINDOWS_KNOWN_ERRORS
 
@@ -47,6 +47,11 @@ from .util import (
 )
 
 
+# typing ----------------------------------------------------------------------
+
+
+# -----------------------------------------------------------------------------
+
 __all__ = ["Submodule", "UpdateProgress"]
 
 
@@ -74,7 +79,7 @@ UPDWKTREE = UpdateProgress.UPDWKTREE
 # IndexObject comes via util module, its a 'hacky' fix thanks to pythons import
 # mechanism which cause plenty of trouble of the only reason for packages and
 # modules is refactoring - subpackages shouldn't depend on parent packages
-class Submodule(IndexObject, Iterable, Traversable):
+class Submodule(IndexObject, IterableObj, Traversable):
 
     """Implements access to a git submodule. They are special in that their sha
     represents a commit in the submodule's repository which is to be checked out
@@ -136,12 +141,12 @@ class Submodule(IndexObject, Iterable, Traversable):
         # END handle attribute name
 
     @classmethod
-    def _get_intermediate_items(cls, item: 'Submodule') -> List['Submodule']:  # type: ignore
+    def _get_intermediate_items(cls, item: 'Submodule') -> IterableList['Submodule']:
         """:return: all the submodules of our module repository"""
         try:
             return cls.list_items(item.module())
         except InvalidGitRepositoryError:
-            return []
+            return IterableList('')
         # END handle intermediate items
 
     @classmethod
@@ -1153,7 +1158,7 @@ class Submodule(IndexObject, Iterable, Traversable):
         """
         return self._name
 
-    def config_reader(self):
+    def config_reader(self) -> SectionConstraint:
         """
         :return: ConfigReader instance which allows you to qurey the configuration values
             of this submodule, as provided by the .gitmodules file
@@ -1163,7 +1168,7 @@ class Submodule(IndexObject, Iterable, Traversable):
         :raise IOError: If the .gitmodules file/blob could not be read"""
         return self._config_parser_constrained(read_only=True)
 
-    def children(self):
+    def children(self) -> IterableList['Submodule']:
         """
         :return: IterableList(Submodule, ...) an iterable list of submodules instances
             which are children of this submodule or 0 if the submodule is not checked out"""
diff --git a/git/objects/submodule/util.py b/git/objects/submodule/util.py
index 0b4ce3c5..b4796b30 100644
--- a/git/objects/submodule/util.py
+++ b/git/objects/submodule/util.py
@@ -4,6 +4,11 @@ from git.config import GitConfigParser
 from io import BytesIO
 import weakref
 
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from .base import Submodule
+
 __all__ = ('sm_section', 'sm_name', 'mkhead', 'find_first_remote_branch',
            'SubmoduleConfigParser')
 
@@ -60,12 +65,12 @@ class SubmoduleConfigParser(GitConfigParser):
         super(SubmoduleConfigParser, self).__init__(*args, **kwargs)
 
     #{ Interface
-    def set_submodule(self, submodule):
+    def set_submodule(self, submodule: 'Submodule') -> None:
         """Set this instance's submodule. It must be called before
         the first write operation begins"""
         self._smref = weakref.ref(submodule)
 
-    def flush_to_index(self):
+    def flush_to_index(self) -> None:
         """Flush changes in our configuration file to the index"""
         assert self._smref is not None
         # should always have a file here