Breaking Change: Use Editions features in Java full runtimes.

This change breaks compatibility with old generated code from previous major versions per the Cross Version Runtime policy: https://protobuf.dev/support/cross-version-runtime-guarantee. This includes old gencode from <4.26.x, which does not resolve features.

See https://protobuf.dev/news/2023-12-05/

PiperOrigin-RevId: 600487923

python/build_targets.bzl

diff --git a/python/build_targets.bzl b/python/build_targets.bzl
index 5f4ae75..a1f1767 100644
--- a/python/build_targets.bzl
+++ b/python/build_targets.bzl
@@ -221,6 +221,7 @@
         testonly = 1,
         srcs = [
             "//:test_proto_srcs",
+            "//:test_proto_editions_srcs",
             "//src/google/protobuf/util:test_proto_srcs",
         ],
         strip_prefix = "src",

python/google/protobuf/internal/descriptor_test.py

diff --git a/python/google/protobuf/internal/descriptor_test.py b/python/google/protobuf/internal/descriptor_test.py
index c561a04..56677d3 100755
--- a/python/google/protobuf/internal/descriptor_test.py
+++ b/python/google/protobuf/internal/descriptor_test.py
@@ -18,11 +18,11 @@
 from google.protobuf import symbol_database
 from google.protobuf import text_format
 from google.protobuf.internal import api_implementation
-from google.protobuf.internal import legacy_features_pb2
 from google.protobuf.internal import test_util
 from google.protobuf.internal import testing_refleaks
 
 from google.protobuf.internal import _parameterized
+from google.protobuf import unittest_legacy_features_pb2
 from google.protobuf import unittest_custom_options_pb2
 from google.protobuf import unittest_features_pb2
 from google.protobuf import unittest_import_pb2
@@ -1268,20 +1268,20 @@
     )
 
   def testFeaturesStripped(self):
-    desc = legacy_features_pb2.TestEditionsMessage.DESCRIPTOR.fields_by_name[
+    desc = unittest_legacy_features_pb2.TestEditionsMessage.DESCRIPTOR.fields_by_name[
         'required_field'
     ]
     self.assertFalse(desc.GetOptions().HasField('features'))
 
   def testLegacyRequiredTransform(self):
-    desc = legacy_features_pb2.TestEditionsMessage.DESCRIPTOR
+    desc = unittest_legacy_features_pb2.TestEditionsMessage.DESCRIPTOR
     self.assertEqual(
         desc.fields_by_name['required_field'].label,
         descriptor.FieldDescriptor.LABEL_REQUIRED,
     )
 
   def testLegacyGroupTransform(self):
-    desc = legacy_features_pb2.TestEditionsMessage.DESCRIPTOR
+    desc = unittest_legacy_features_pb2.TestEditionsMessage.DESCRIPTOR
     self.assertEqual(
         desc.fields_by_name['delimited_field'].type,
         descriptor.FieldDescriptor.TYPE_GROUP,

python/google/protobuf/internal/legacy_features.proto

diff --git a/python/google/protobuf/internal/legacy_features.proto b/python/google/protobuf/internal/legacy_features.proto
deleted file mode 100644
index ef803dd..0000000
--- a/python/google/protobuf/internal/legacy_features.proto
+++ /dev/null
@@ -1,18 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2008 Google Inc.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-
-// Test that features with legacy descriptor helpers get properly converted.
-
-edition = "2023";
-
-package google.protobuf.internal;
-
-message TestEditionsMessage {
-  int32 required_field = 1 [features.field_presence = LEGACY_REQUIRED];
-  TestEditionsMessage delimited_field = 2
-      [features.message_encoding = DELIMITED];
-}