Create some tests for GetClassName for edition < 2024 so that we can make sure these invariants won't be changed/broken when merging to the edition 2024 feature implementations.

PiperOrigin-RevId: 691010930

src/google/protobuf/compiler/java/test_multiple_file_no.proto

@@ -0,0 +1,20 @@
+edition = "2023";
+
+package protobuf_unittest;
+
+// Test generic services that are produced by the protoc builtin generators.
+option cc_generic_services = true;
+option java_generic_services = true;
+
+enum MultipleFileNoEnum {
+  MULTIPLE_FILE_NO_BAR = 0;
+}
+
+message MultipleFileNoMessage {
+  int32 bar = 1;
+}
+
+service MultipleFileNoService {
+  // Test.
+  rpc Method(MultipleFileNoMessage) returns (MultipleFileNoMessage) {}
+}

src/google/protobuf/compiler/java/test_multiple_file_yes.proto

@@ -0,0 +1,21 @@
+edition = "2023";
+
+package protobuf_unittest;
+
+// Test generic services that are produced by the protoc builtin generators.
+option cc_generic_services = true;
+option java_generic_services = true;
+option java_multiple_files = true;
+
+enum MultipleFileYesEnum {
+  MULTIPLE_FILE_YES_BAR = 0;
+}
+
+message MultipleFileYesMessage {
+  int32 bar = 1;
+}
+
+service MultipleFileYesService {
+  // Test.
+  rpc Method(MultipleFileYesMessage) returns (MultipleFileYesMessage) {}
+}