Add selected copies of old java gencode for smoke test

Also remove the 'optional' keyword from the proto3 test file for this purpose, since most of these versions predate proto3-optional. In the future if we expand this to cover more including Editions we will need to add some mechanism for when the given .proto file started being supported which would also generalize to proto3-optional if we want coverage of that specific case.

PiperOrigin-RevId: 814687967

Author: protobuf-github-bot

compatibility/smoke/BUILD.bazel

@@ -1,4 +1,18 @@
 load("@rules_java//java:defs.bzl", "java_test")
 load("//compatibility/smoke:stale_gencode_smoke_test.bzl", "stale_gencode_smoke_test")
 
+stale_gencode_smoke_test("3.8.0")
+
+stale_gencode_smoke_test("3.11.0")
+
 stale_gencode_smoke_test("3.19.0")
+
+stale_gencode_smoke_test("3.20.0")
+
+stale_gencode_smoke_test("21.12")  # Patch release chosen because patches on 21.x added CVE fixes.
+
+stale_gencode_smoke_test("25.8")  # Patch release with CVE fixes and the likely final PBJ 3.x release.
+
+stale_gencode_smoke_test("26.0")
+
+stale_gencode_smoke_test("32.1")

compatibility/smoke/proto3_gencode_test.proto

@@ -5,7 +5,7 @@ package legacy_gencode_test.proto3;
 option java_outer_classname = "Proto3GencodeTestProto";
 
 message TestMessage {
-  optional string x = 2;
+  string x = 2;
   NestedTestMessage y = 3;
 }
 

compatibility/smoke/v21.12/BUILD.bazel

@@ -0,0 +1,8 @@
+load("@rules_java//java:java_library.bzl", "java_library")
+
+java_library(
+    name = "checked_in_gencode",
+    srcs = glob(["**/*.java"]),
+    visibility = ["//compatibility:__subpackages__"],
+    deps = ["//:protobuf_java"],
+)