Add conformance test cases about handling of google.protobuf.Empty inside any Any in JSON.

As of today:
- GoProto and C# serialize google.protobuf.Empty-packed-into-Any with the `"value":{}` field set
- Only Go, C# and Swift accept that shape at parse time

In an attempt to make spec match reality, the public ProtoJSON documentation has now been clarified to match the common behavior that nearly all implementations have in practice.

Note that this conformance test added is only mandating that implementations:
1) Accept it without the `"value":{}` set
2) Serialize it without it set (by virtue of the round trip coming back to C++Proto in the test harness which does not accept it).

A test that confirms an implementation affirmatively rejects if the "value":{} is set is not added here; especially in the near term it is sensible for implementations like Go and C# to locally continue to accept that shape for backwards compatibility reasons within the same language, as long as it emits without it by default so that other languages can parse what it emits. For that reason, a test affirming a parse failure when it is present is not added to the conformance test suite failure today.

#24445

PiperOrigin-RevId: 854155587

Author: protobuf-github-bot

conformance/binary_json_conformance_suite.cc

@@ -16,7 +16,6 @@
 #include <string>
 #include <type_traits>
 #include <utility>
-#include <vector>
 
 #include "absl/log/absl_check.h"
 #include "absl/log/absl_log.h"
@@ -3685,6 +3684,22 @@ void BinaryAndJsonConformanceSuiteImpl<MessageType>::RunJsonTestsForAny() {
       })",
                    R"(
       )");
+
+  // google.protobuf.Empty packed into an Any, implementations must accept it
+  // without the "value" field set. This also confirms that what they round trip
+  // does not have `"value":{}` set on it, since the test harness uses the C++
+  // JSON parser which will reject it.
+  RunValidJsonTest("AnyEmpty", REQUIRED,
+                   R"({
+        "optionalAny": {
+          "@type": "type.googleapis.com/google.protobuf.Empty"
+        }
+      })",
+                   R"(
+        optional_any: {
+          [type.googleapis.com/google.protobuf.Empty] {}
+        }
+      )");
 }
 
 template <typename MessageType>

conformance/failure_list_csharp.txt

@@ -40,4 +40,4 @@ Required.Editions_Proto3.ProtobufInput.UnknownOrdering.ProtobufOutput
 Required.*.ProtobufInput.BadTag_FieldNumberTooHigh                                                                 # Should have failed to parse, but didn't.
 Required.*.ProtobufInput.BadTag_FieldNumberSlightlyTooHigh                                                         # Should have failed to parse, but didn't.
 Required.*.ProtobufInput.BadTag_OverlongVarint                                                                     # Should have failed to parse, but didn't.
-
+Required.*.JsonInput.AnyEmpty.*

editions/BUILD

@@ -258,6 +258,7 @@ proto_library(
     deps = [
         "//:any_proto",
         "//:duration_proto",
+        "//:empty_proto",
         "//:field_mask_proto",
         "//:struct_proto",
         "//:timestamp_proto",

editions/golden/edition2023_transform/test_messages_proto3.proto

@@ -18,6 +18,7 @@ package protobuf_test_messages.proto3;
 
 import "google/protobuf/any.proto";
 import "google/protobuf/duration.proto";
+import "google/protobuf/empty.proto";
 import "google/protobuf/field_mask.proto";
 import "google/protobuf/struct.proto";
 import "google/protobuf/timestamp.proto";
@@ -255,13 +256,15 @@ message TestAllTypesProto3 {
   google.protobuf.Any optional_any = 305;
   google.protobuf.Value optional_value = 306;
   google.protobuf.NullValue optional_null_value = 307;
+  google.protobuf.Empty optional_empty = 308;
   repeated google.protobuf.Duration repeated_duration = 311;
   repeated google.protobuf.Timestamp repeated_timestamp = 312;
   repeated google.protobuf.FieldMask repeated_fieldmask = 313;
   repeated google.protobuf.Struct repeated_struct = 324;
   repeated google.protobuf.Any repeated_any = 315;
   repeated google.protobuf.Value repeated_value = 316;
   repeated google.protobuf.ListValue repeated_list_value = 317;
+  repeated google.protobuf.Empty repeated_empty = 318;
 
   // Test field-name-to-JSON-name convention.
   // (protobuf says names can be any valid C/C++ identifier.)

editions/golden/edition2024_transform/test_messages_proto3.proto

@@ -19,6 +19,7 @@ package protobuf_test_messages.proto3;
 
 import "google/protobuf/any.proto";
 import "google/protobuf/duration.proto";
+import "google/protobuf/empty.proto";
 import "google/protobuf/field_mask.proto";
 import "google/protobuf/struct.proto";
 import "google/protobuf/timestamp.proto";
@@ -268,13 +269,15 @@ message TestAllTypesProto3 {
   google.protobuf.Any optional_any = 305;
   google.protobuf.Value optional_value = 306;
   google.protobuf.NullValue optional_null_value = 307;
+  google.protobuf.Empty optional_empty = 308;
   repeated google.protobuf.Duration repeated_duration = 311;
   repeated google.protobuf.Timestamp repeated_timestamp = 312;
   repeated google.protobuf.FieldMask repeated_fieldmask = 313;
   repeated google.protobuf.Struct repeated_struct = 324;
   repeated google.protobuf.Any repeated_any = 315;
   repeated google.protobuf.Value repeated_value = 316;
   repeated google.protobuf.ListValue repeated_list_value = 317;
+  repeated google.protobuf.Empty repeated_empty = 318;
 
   // Test field-name-to-JSON-name convention.
   // (protobuf says names can be any valid C/C++ identifier.)

editions/golden/test_messages_proto3_editions.proto

@@ -18,6 +18,7 @@ package protobuf_test_messages.editions.proto3;
 
 import "google/protobuf/any.proto";
 import "google/protobuf/duration.proto";
+import "google/protobuf/empty.proto";
 import "google/protobuf/field_mask.proto";
 import "google/protobuf/struct.proto";
 import "google/protobuf/timestamp.proto";
@@ -255,13 +256,15 @@ message TestAllTypesProto3 {
   google.protobuf.Any optional_any = 305;
   google.protobuf.Value optional_value = 306;
   google.protobuf.NullValue optional_null_value = 307;
+  google.protobuf.Empty optional_empty = 308;
   repeated google.protobuf.Duration repeated_duration = 311;
   repeated google.protobuf.Timestamp repeated_timestamp = 312;
   repeated google.protobuf.FieldMask repeated_fieldmask = 313;
   repeated google.protobuf.Struct repeated_struct = 324;
   repeated google.protobuf.Any repeated_any = 315;
   repeated google.protobuf.Value repeated_value = 316;
   repeated google.protobuf.ListValue repeated_list_value = 317;
+  repeated google.protobuf.Empty repeated_empty = 318;
 
   // Test field-name-to-JSON-name convention.
   // (protobuf says names can be any valid C/C++ identifier.)

src/google/protobuf/BUILD.bazel

@@ -1374,6 +1374,7 @@ proto_library(
     deps = [
         ":any_proto",
         ":duration_proto",
+        ":empty_proto",
         ":field_mask_proto",
         ":struct_proto",
         ":timestamp_proto",

src/google/protobuf/test_messages_proto3.proto

@@ -24,6 +24,7 @@ option optimize_for = SPEED;
 
 import "google/protobuf/any.proto";
 import "google/protobuf/duration.proto";
+import "google/protobuf/empty.proto";
 import "google/protobuf/field_mask.proto";
 import "google/protobuf/struct.proto";
 import "google/protobuf/timestamp.proto";
@@ -212,6 +213,7 @@ message TestAllTypesProto3 {
   google.protobuf.Any optional_any = 305;
   google.protobuf.Value optional_value = 306;
   google.protobuf.NullValue optional_null_value = 307;
+  google.protobuf.Empty optional_empty = 308;
 
   repeated google.protobuf.Duration repeated_duration = 311;
   repeated google.protobuf.Timestamp repeated_timestamp = 312;
@@ -220,6 +222,7 @@ message TestAllTypesProto3 {
   repeated google.protobuf.Any repeated_any = 315;
   repeated google.protobuf.Value repeated_value = 316;
   repeated google.protobuf.ListValue repeated_list_value = 317;
+  repeated google.protobuf.Empty repeated_empty = 318;
 
   // Test field-name-to-JSON-name convention.
   // (protobuf says names can be any valid C/C++ identifier.)