fix baggage propagation for empty/invalid baggage context (#1367)

api/include/opentelemetry/baggage/propagation/baggage_propagator.h

@@ -21,15 +21,27 @@ class BaggagePropagator : public opentelemetry::context::propagation::TextMapPro
               const opentelemetry::context::Context &context) noexcept override
   {
     auto baggage = opentelemetry::baggage::GetBaggage(context);
-    carrier.Set(kBaggageHeader, baggage->ToHeader());
+    auto header  = baggage->ToHeader();
+    if (header.size())
+    {
+      carrier.Set(kBaggageHeader, header);
+    }
   }
 
   context::Context Extract(const opentelemetry::context::propagation::TextMapCarrier &carrier,
                            opentelemetry::context::Context &context) noexcept override
   {
     nostd::string_view baggage_str = carrier.Get(opentelemetry::baggage::kBaggageHeader);
     auto baggage                   = opentelemetry::baggage::Baggage::FromHeader(baggage_str);
-    return opentelemetry::baggage::SetBaggage(context, baggage);
+
+    if (baggage->ToHeader().size())
+    {
+      return opentelemetry::baggage::SetBaggage(context, baggage);
+    }
+    else
+    {
+      return context;
+    }
   }
 
   bool Fields(nostd::function_ref<bool(nostd::string_view)> callback) const noexcept override

api/test/baggage/propagation/baggage_propagator_test.cc

@@ -82,3 +82,32 @@ TEST(BaggagePropagatorTest, ExtractAndInjectBaggage)
     EXPECT_EQ(fields[0], baggage::kBaggageHeader.data());
   }
 }
+
+TEST(BaggagePropagatorTest, InjectEmptyHeader)
+{
+  // Test Missing baggage from context
+  BaggageCarrierTest carrier;
+  context::Context ctx = context::Context{};
+  format.Inject(carrier, ctx);
+  EXPECT_EQ(carrier.headers_.find(baggage::kBaggageHeader), carrier.headers_.end());
+
+  {
+    // Test empty baggage in context
+    BaggageCarrierTest carrier1;
+    carrier1.headers_[baggage::kBaggageHeader.data()] = "";
+    context::Context ctx1                             = context::Context{};
+    context::Context ctx2                             = format.Extract(carrier1, ctx1);
+    format.Inject(carrier, ctx2);
+    EXPECT_EQ(carrier.headers_.find(baggage::kBaggageHeader), carrier.headers_.end());
+  }
+  {
+    // Invalid baggage in context
+    BaggageCarrierTest carrier1;
+    carrier1.headers_[baggage::kBaggageHeader.data()] = "InvalidBaggageData";
+    context::Context ctx1                             = context::Context{};
+    context::Context ctx2                             = format.Extract(carrier1, ctx1);
+
+    format.Inject(carrier, ctx2);
+    EXPECT_EQ(carrier.headers_.find(baggage::kBaggageHeader), carrier.headers_.end());
+  }
+}