refactor: Annotate methods which may return null with @Nullable

Use this link to re-run the recipe: https://app.moderne.io/recipes/org.openrewrite.staticanalysis.AnnotateNullableMethods?organizationId=ODQ2MGExMTUtNDg0My00N2EwLTgzMGMtNGE1NGExMTBmZDkw

Co-authored-by: Moderne <team@moderne.io>

Author: timtebeek

rewrite-python/src/main/java/org/openrewrite/python/PythonVisitor.java

@@ -480,7 +480,7 @@ public J visitSlice(Py.Slice slice, P p) {
         return slice;
     }
 
-    public <J2 extends J> JContainer<J2> visitContainer(@Nullable JContainer<J2> container,
+    public <J2 extends J> @Nullable JContainer<J2> visitContainer(@Nullable JContainer<J2> container,
                                                         PyContainer.Location loc, P p) {
         if (container == null) {
             //noinspection ConstantConditions
@@ -498,7 +498,7 @@ public <J2 extends J> JContainer<J2> visitContainer(@Nullable JContainer<J2> con
                 JContainer.build(before, js, container.getMarkers());
     }
 
-    public <T> JLeftPadded<T> visitLeftPadded(@Nullable JLeftPadded<T> left, PyLeftPadded.Location loc, P p) {
+    public <T> @Nullable JLeftPadded<T> visitLeftPadded(@Nullable JLeftPadded<T> left, PyLeftPadded.Location loc, P p) {
         if (left == null) {
             //noinspection ConstantConditions
             return null;
@@ -527,7 +527,7 @@ public <T> JLeftPadded<T> visitLeftPadded(@Nullable JLeftPadded<T> left, PyLeftP
         return (before == left.getBefore() && t == left.getElement()) ? left : new JLeftPadded<>(before, t, left.getMarkers());
     }
 
-    public <T> JRightPadded<T> visitRightPadded(@Nullable JRightPadded<T> right, PyRightPadded.Location loc, P p) {
+    public <T> @Nullable JRightPadded<T> visitRightPadded(@Nullable JRightPadded<T> right, PyRightPadded.Location loc, P p) {
         if (right == null) {
             //noinspection ConstantConditions
             return null;