Extract legacy native symbols to a separate bzl file

`legacy_native.bzl` will only be used by the compatibility proxy for Bazel versions < 8, and will thus allow removing these symbols from Bazel@HEAD. `native.bzl` now only exposes the `java_common` private APIs.

PiperOrigin-RevId: 726035093
Change-Id: I8c78164b2b7ce9b647b2a7d195850213a85a8b86

java/private/BUILD

diff --git a/java/private/BUILD b/java/private/BUILD
index 020a4a7..27be00d 100644
--- a/java/private/BUILD
+++ b/java/private/BUILD
@@ -7,10 +7,15 @@
     srcs = [
         "native.bzl",
     ],
-    visibility = [
-        "//java:__subpackages__",
-        "@compatibility_proxy//:__pkg__",
+    visibility = ["//java:__subpackages__"],
+)
+
+bzl_library(
+    name = "legacy_native_bzl",
+    srcs = [
+        "legacy_native.bzl",
     ],
+    visibility = ["@compatibility_proxy//:__pkg__"],
 )
 
 bzl_library(

java/private/legacy_native.bzl

diff --git a/java/private/legacy_native.bzl b/java/private/legacy_native.bzl
new file mode 100644
index 0000000..7a9e62f
--- /dev/null
+++ b/java/private/legacy_native.bzl
@@ -0,0 +1,29 @@
+# Copyright 2022 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Redefine native symbols with a new name as a workaround for
+# exporting them in @compatibility_proxy//:proxy.bzl with their original name.
+
+"""Lovely workaround to be able to expose native constants pretending to be Starlark."""
+
+# Unused with Bazel@HEAD, only used by the compatibility layer for older Bazel versions
+
+# buildifier: disable=native-java-common
+native_java_common = java_common
+
+# buildifier: disable=native-java-info
+NativeJavaInfo = JavaInfo
+
+# buildifier: disable=native-java-plugin-info
+NativeJavaPluginInfo = JavaPluginInfo

java/private/native.bzl

diff --git a/java/private/native.bzl b/java/private/native.bzl
index e6be6f7..be7ae68 100644
--- a/java/private/native.bzl
+++ b/java/private/native.bzl
@@ -12,29 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Redefine native symbols with a new name as a workaround for
-# exporting them in `//third_party/bazel_rules/rules_proto/proto:defs.bzl` with their original name.
-#
-# While we cannot force users to load these symbol due to the lack of a
-# allowlisting mechanism, we can still export them and tell users to
-# load it to make a future migration to pure Starlark easier.
-
-"""Lovely workaround to be able to expose native constants pretending to be Starlark."""
-
-# Unused with Bazel@HEAD, used by the compatibility layer for older Bazel versions
-
-# buildifier: disable=native-java-common
-native_java_common = java_common
-
-# buildifier: disable=native-java-info
-NativeJavaInfo = JavaInfo
-
-# buildifier: disable=native-java-plugin-info
-NativeJavaPluginInfo = JavaPluginInfo
+"""Redirects for private native APIs"""
 
 # Used for some private native APIs that we can't replicate just yet in Starlark
-# getattr() for loading this file with Bazel 6, where we won't use this
 def get_internal_java_common():
-    if hasattr(native_java_common, "internal_DO_NOT_USE"):
-        return native_java_common.internal_DO_NOT_USE()
-    return None
+    return java_common.internal_DO_NOT_USE()  # buildifier: disable=native-java-common

java/rules_java_deps.bzl

diff --git a/java/rules_java_deps.bzl b/java/rules_java_deps.bzl
index 1929bc8..b088f4d 100644
--- a/java/rules_java_deps.bzl
+++ b/java/rules_java_deps.bzl
@@ -69,7 +69,7 @@
     name = "proxy_bzl",
     srcs = ["proxy.bzl"],
     deps = [
-        "@rules_java//java/private:native_bzl",
+        "@rules_java//java/private:legacy_native_bzl",
         "@bazel_tools//tools:bzl_srcs",
     ],
     visibility = ["//visibility:public"]
@@ -80,7 +80,7 @@
             "proxy.bzl",
             """
 load("@bazel_tools//tools/build_defs/repo:http.bzl", _http_jar = "http_jar")
-load("@rules_java//java/private:native.bzl", "native_java_common", "NativeJavaInfo", "NativeJavaPluginInfo")
+load("@rules_java//java/private:legacy_native.bzl", "native_java_common", "NativeJavaInfo", "NativeJavaPluginInfo")
 
 java_binary = native.java_binary
 java_import = native.java_import