feat: re-enable Java example of using pre-built protoc

Author: alexeagle

examples/java/BUILD

@@ -1,10 +1,9 @@
-# See comment in examples/BUILD.bazel
-# java_binary(
-#     name = "java",
-#     srcs = ["Main.java"],
-#     main_class = "Main",
-#     deps = [
-#         "//:foo_java_proto",
-#         "@protobuf-java//jar",
-#     ],
-# )
+java_binary(
+    name = "java",
+    srcs = ["Main.java"],
+    main_class = "Main",
+    deps = [
+        "//proto:greeter_java_proto",
+        "@protobuf-java//jar",
+    ],
+)

examples/java/Main.java

@@ -1,14 +1,14 @@
 import com.google.protobuf.InvalidProtocolBufferException;
-import static proto.FooOuterClass.Foo;
+import static proto.GreeterOuterClass.HelloRequest;
 
 public class Main {
   public static void main(String[] args) throws InvalidProtocolBufferException {
     System.out.println(makeMessage("Hello World!"));
   }
 
-  public static Foo makeMessage(String msg) {
-    Foo.Builder person = Foo.newBuilder();
-    person.setMsg(msg);
-    return person.build();
+  public static HelloRequest makeMessage(String msg) {
+    HelloRequest.Builder req = HelloRequest.newBuilder();
+    req.setName(msg);
+    return req.build();
   }
 }

examples/proto/BUILD.bazel

@@ -1,8 +1,9 @@
 load("@aspect_rules_ts//ts:proto.bzl", "ts_proto_library")
+load("@protobuf//bazel:java_proto_library.bzl", "java_proto_library")
+load("@protobuf//bazel:py_proto_library.bzl", "py_proto_library")
 load("@rules_go//proto:def.bzl", "go_proto_library")
 load("@rules_proto//proto:defs.bzl", "proto_library")
 load("@rules_rust_prost//:defs.bzl", "rust_prost_library")
-load("@protobuf//bazel:py_proto_library.bzl", "py_proto_library")
 
 package(default_visibility = ["//visibility:public"])
 
@@ -19,11 +20,10 @@ py_proto_library(
 
 # Broken by https://github.com/protocolbuffers/protobuf/pull/19679
 # which causes building C++ code from source.
-# TODO: re-enable once protobuf honors the toolchain
-# java_proto_library(
-#     name = "greeter_java_proto",
-#     deps = [":greeter_proto"],
-# )
+java_proto_library(
+    name = "greeter_java_proto",
+    deps = [":greeter_proto"],
+)
 
 go_proto_library(
     name = "greeter_go_proto",