Merge ~andrey-fedoseev/lazr.restful:allow-none-for-lists into lazr.restful:main

[Andrey Fedoseev]

The collection marshallers can now unmarshall None

The collection marshallers (list, set, tuple) will now correctly
unmarshall `None` as `None`.

Previously, they would raise a `TypeError` when calling with `None`

[Colin Watson (cjwatson)]

review: Approve

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 6b363b1..4d505fe 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -25,6 +25,6 @@ repos:
     -   id: pyupgrade
         args: [--keep-percent-format, --py3-plus]
 -   repo: https://github.com/psf/black
-    rev: 21.10b0
+    rev: 22.3.0
     hooks:
     - id: black
diff --git a/NEWS.rst b/NEWS.rst
index 6e42cce..d1817d2 100644
--- a/NEWS.rst
+++ b/NEWS.rst
@@ -2,9 +2,10 @@
 NEWS for lazr.restful
 =====================
 
-1.2.0
-=====
+2.0.0 (2022-06-01)
+==================
 
+- Drop Python 2 support.
 - Add support for Python 3.9 and 3.10.
 - Add basic pre-commit configuration.
 - Publish docs on Read the Docs.
@@ -19,7 +20,6 @@ NEWS for lazr.restful
   ``lazr.restful.testing.webservice.DummyRootResourceURL``
   => ``lazr.restful.testing.webservice.StubRootResourceURL``
 - Apply black code formatter via pre-commit.
-- Drop Python 2 support.
 - Remove ``export_as_webservice_entry`` and
   ``export_as_webservice_collection``; these were deprecated in 0.22.0 and
   cannot work on Python 3.  Use the class decorators
@@ -27,6 +27,8 @@ NEWS for lazr.restful
   ``@exported_as_webservice_collection`` instead.
 - Deprecate ``lazr.restful.utils.safe_hasattr``, since Python's builtin
   ``hasattr`` is fixed as of Python 3.2.
+- The collection marshallers (list, set, tuple) will now correctly
+  unmarshall ``None`` as ``None``.
 
 1.1.0 (2021-10-07)
 ==================
diff --git a/setup.py b/setup.py
index c21f37a..e8602b8 100755
--- a/setup.py
+++ b/setup.py
@@ -38,7 +38,7 @@ def generate(*docname_or_string):
 
 setup(
     name="lazr.restful",
-    version="1.1.0",
+    version="2.0.0",
     namespace_packages=["lazr"],
     packages=find_packages("src"),
     package_dir={"": "src"},
diff --git a/src/lazr/restful/docs/webservice-marshallers.rst b/src/lazr/restful/docs/webservice-marshallers.rst
index b32e0d2..c99a36c 100644
--- a/src/lazr/restful/docs/webservice-marshallers.rst
+++ b/src/lazr/restful/docs/webservice-marshallers.rst
@@ -984,6 +984,15 @@ The unmarshall() method will return None when given None.
     >>> print(dict_marshaller.unmarshall(None, None))
     None
 
+    >>> print(list_marshaller.unmarshall(None, None))
+    None
+
+    >>> print(set_marshaller.unmarshall(None, None))
+    None
+
+    >>> print(tuple_marshaller.unmarshall(None, None))
+    None
+
 CollectionField
 ---------------
 
diff --git a/src/lazr/restful/marshallers.py b/src/lazr/restful/marshallers.py
index 3279657..2ca4e34 100644
--- a/src/lazr/restful/marshallers.py
+++ b/src/lazr/restful/marshallers.py
@@ -511,6 +511,9 @@ class AbstractCollectionFieldMarshaller(SimpleFieldMarshaller):
         The collection is unmarshalled into a list and all its items are
         unmarshalled using the appropriate FieldMarshaller.
         """
+        if value is None:
+            return value
+
         return [
             self.value_marshaller.unmarshall(entry, item) for item in value
         ]