code review changes

src/core/client_channel/lb_metadata.cc

@@ -75,7 +75,7 @@ LbMetadata::TestOnlyCopyToVector() const {
 void MetadataMutationHandler::Apply(
     LoadBalancingPolicy::MetadataMutations& metadata_mutations,
     grpc_metadata_batch* metadata) {
-  for (auto& p : metadata_mutations.additions_) {
+  for (auto& p : metadata_mutations.metadata_) {
     absl::string_view key = p.first;
     Slice& value =
         grpc_event_engine::experimental::internal::SliceCast<Slice>(p.second);

src/core/load_balancing/grpclb/grpclb.cc

@@ -778,7 +778,7 @@ GrpcLb::PickResult GrpcLb::Picker::Pick(PickArgs args) {
       // a string and rely on the client_load_reporting filter to know
       // how to interpret it.
       // NOLINTBEGIN(bugprone-string-constructor)
-      complete_pick->metadata_mutations.Add(
+      complete_pick->metadata_mutations.Set(
           GrpcLbClientStatsMetadata::key(),
           grpc_event_engine::experimental::Slice(grpc_slice_from_static_buffer(
               reinterpret_cast<const char*>(client_stats), 0)));
@@ -791,7 +791,7 @@ GrpcLb::PickResult GrpcLb::Picker::Pick(PickArgs args) {
     // may get refreshed between when we return this pick and when the
     // initial metadata goes out on the wire.
     if (!subchannel_wrapper->lb_token().empty()) {
-      complete_pick->metadata_mutations.Add(
+      complete_pick->metadata_mutations.Set(
           LbTokenMetadata::key(), subchannel_wrapper->lb_token().Ref());
     }
     // Unwrap subchannel to pass up to the channel.

src/core/load_balancing/lb_policy.h

@@ -124,14 +124,14 @@ class LoadBalancingPolicy : public InternallyRefCounted<LoadBalancingPolicy> {
   /// A list of metadata mutations to be returned along with a PickResult.
   class MetadataMutations {
    public:
-    /// Adds a key/value pair.  If the key is already present, it will
+    /// Sets a key/value pair.  If the key is already present, it will
     /// be replaced with the new value.
-    void Add(absl::string_view key, absl::string_view value) {
-      Add(key, grpc_event_engine::experimental::Slice::FromCopiedString(value));
+    void Set(absl::string_view key, absl::string_view value) {
+      Set(key, grpc_event_engine::experimental::Slice::FromCopiedString(value));
     }
-    void Add(absl::string_view key,
+    void Set(absl::string_view key,
              grpc_event_engine::experimental::Slice value) {
-      additions_.push_back({key, std::move(value)});
+      metadata_.push_back({key, std::move(value)});
     }
 
    private:
@@ -143,7 +143,7 @@ class LoadBalancingPolicy : public InternallyRefCounted<LoadBalancingPolicy> {
     // cases with more than 3 additions.
     absl::InlinedVector<
         std::pair<absl::string_view, grpc_event_engine::experimental::Slice>, 3>
-        additions_;
+        metadata_;
   };
 
   /// Arguments used when picking a subchannel for a call.

src/core/load_balancing/rls/rls.cc

@@ -1265,7 +1265,7 @@ LoadBalancingPolicy::PickResult RlsLb::Cache::Entry::Pick(PickArgs args) {
     auto* complete_pick =
         absl::get_if<PickResult::Complete>(&pick_result.result);
     if (complete_pick != nullptr) {
-      complete_pick->metadata_mutations.Add(kRlsHeaderKey, header_data_.Ref());
+      complete_pick->metadata_mutations.Set(kRlsHeaderKey, header_data_.Ref());
     }
   }
   return pick_result;

test/core/client_channel/lb_metadata_test.cc

@@ -29,25 +29,25 @@ namespace grpc_core {
 namespace testing {
 namespace {
 
-TEST(LbMetadataMutation, AddsUnknownHeader) {
+TEST(LbMetadataMutation, SetsUnknownHeader) {
   grpc_metadata_batch metadata;
   LoadBalancingPolicy::MetadataMutations mutations;
-  mutations.Add("key", "value");
+  mutations.Set("key", "value");
   MetadataMutationHandler::Apply(mutations, &metadata);
   std::string buffer;
   EXPECT_EQ(metadata.GetStringValue("key", &buffer), "value");
 }
 
-TEST(LbMetadataMutation, AddsTraitHeader) {
+TEST(LbMetadataMutation, SetsTraitHeader) {
   grpc_metadata_batch metadata;
   LoadBalancingPolicy::MetadataMutations mutations;
-  mutations.Add("user-agent", "value");
+  mutations.Set("user-agent", "value");
   MetadataMutationHandler::Apply(mutations, &metadata);
   std::string buffer;
   EXPECT_EQ(metadata.GetStringValue("user-agent", &buffer), "value");
 }
 
-TEST(LbMetadataMutation, OverwritesExistingKeys) {
+TEST(LbMetadataMutation, OverwritesExistingHeader) {
   grpc_metadata_batch metadata;
   metadata.Append("key", Slice::FromCopiedString("value1"),
                   [&](absl::string_view error, const Slice& value) {
@@ -60,12 +60,12 @@ TEST(LbMetadataMutation, OverwritesExistingKeys) {
   std::string buffer;
   EXPECT_EQ(metadata.GetStringValue("key", &buffer), "value1,value2");
   LoadBalancingPolicy::MetadataMutations mutations;
-  mutations.Add("key", "value3");
+  mutations.Set("key", "value3");
   MetadataMutationHandler::Apply(mutations, &metadata);
   EXPECT_EQ(metadata.GetStringValue("key", &buffer), "value3");
 }
 
-TEST(LbMetadataMutation, OverwritesTraitKeys) {
+TEST(LbMetadataMutation, OverwritesTraitHeader) {
   grpc_metadata_batch metadata;
   metadata.Append("user-agent", Slice::FromCopiedString("value1"),
                   [&](absl::string_view error, const Slice& value) {
@@ -74,7 +74,7 @@ TEST(LbMetadataMutation, OverwritesTraitKeys) {
   std::string buffer;
   EXPECT_EQ(metadata.GetStringValue("user-agent", &buffer), "value1");
   LoadBalancingPolicy::MetadataMutations mutations;
-  mutations.Add("user-agent", "value2");
+  mutations.Set("user-agent", "value2");
   MetadataMutationHandler::Apply(mutations, &metadata);
   EXPECT_EQ(metadata.GetStringValue("user-agent", &buffer), "value2");
 }

test/cpp/interop/rpc_behavior_lb_policy.cc

@@ -117,7 +117,7 @@ class RpcBehaviorLbPolicy : public LoadBalancingPolicy {
       auto* complete_pick =
           absl::get_if<PickResult::Complete>(&pick_result.result);
       if (complete_pick != nullptr) {
-        complete_pick->metadata_mutations.Add(kRpcBehaviorMetadataKey,
+        complete_pick->metadata_mutations.Set(kRpcBehaviorMetadataKey,
                                               rpc_behavior_);
       }
       // Return result.