Remove synthetic oneofs from Java gencode field accessor tables.

This is needed to unblock Java editions codegen tests, due to codegen diff for proto3 optionals migrated to editions.

This is incompatible with runtimes <24.x, but our cross-version support policy explicitly does not guarantee compatibility for new gencode with old runtimes: https://protobuf.dev/support/cross-version-runtime-guarantee/#minor

PiperOrigin-RevId: 572578693

src/google/protobuf/compiler/java/message.cc

@@ -224,10 +224,9 @@ int ImmutableMessageGenerator::GenerateFieldAccessorTableInitializer(
     bytecode_estimate += 6;
     printer->Print("\"$field_name$\", ", "field_name", info->capitalized_name);
   }
-  // TODO: Once cl/534906231 propagates, only consider real oneofs
-  // since proto reflection does not use this for synthetic oneofs.
-  for (int i = 0; i < descriptor_->oneof_decl_count(); i++) {
-    const OneofDescriptor* oneof = descriptor_->oneof_decl(i);
+
+  for (int i = 0; i < descriptor_->real_oneof_decl_count(); i++) {
+    const OneofDescriptor* oneof = descriptor_->real_oneof_decl(i);
     const OneofGeneratorInfo* info = context_->GetOneofGeneratorInfo(oneof);
     bytecode_estimate += 6;
     printer->Print("\"$oneof_name$\", ", "oneof_name", info->capitalized_name);