make extracted spans a list and allow overwriting headers in the map

Author: mabdinur

test/system-tests/request_handler.cpp

@@ -256,9 +256,9 @@ void RequestHandler::on_extract_headers(const httplib::Request& req,
   // clang-format on
 
   res.set_content(response_body.dump(), "application/json");
-  http_headers_.emplace(span->parent_id().value(), std::move(*http_headers));
+  http_headers_[span->parent_id().value()] = std::move(*http_headers);
   // The span below will not be finished and flushed.
-  extract_headers_spans_.emplace(span->parent_id().value(), std::move(*span));
+  extract_headers_spans_.push_back(std::move(*span));
 }
 
 void RequestHandler::on_span_flush(const httplib::Request& /* req */,

test/system-tests/request_handler.h

@@ -38,7 +38,7 @@ class RequestHandler final {
   std::shared_ptr<ManualScheduler> scheduler_;
   std::shared_ptr<DeveloperNoiseLogger> logger_;
   std::unordered_map<uint64_t, datadog::tracing::Span> active_spans_;
-  std::unordered_map<uint64_t, datadog::tracing::Span> extract_headers_spans_;
+  std::vector<datadog::tracing::Span> extract_headers_spans_;
   std::unordered_map<uint64_t, nlohmann::json::array_t> http_headers_;
 
 #undef VALIDATION_ERROR