Fix route handling when local root span wasn't created by instrumentation api (#13588)

Author: laurit

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/Instrumenter.java

@@ -190,7 +190,8 @@ private Context doStart(Context parentContext, REQUEST request, @Nullable Instan
       context = contextCustomizer.onStart(context, request, attributes);
     }
 
-    boolean localRoot = LocalRootSpan.isLocalRoot(context);
+    boolean localRoot = LocalRootSpan.isLocalRoot(parentContext);
+    boolean hasLocalRoot = LocalRootSpan.fromContextOrNull(context) != null;
 
     spanBuilder.setAllAttributes(attributes);
     Span span = spanBuilder.setParent(context).startSpan();
@@ -216,9 +217,9 @@ private Context doStart(Context parentContext, REQUEST request, @Nullable Instan
 
     if (localRoot) {
       context = LocalRootSpan.store(context, span);
-      if (spanKind == SpanKind.SERVER) {
-        HttpRouteState.updateSpan(context, span);
-      }
+    }
+    if (!hasLocalRoot && spanKind == SpanKind.SERVER) {
+      HttpRouteState.updateSpan(context, span);
     }
 
     return spanSuppressor.storeInContext(context, spanKind, span);

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/HttpRouteState.java

@@ -27,7 +27,7 @@ public static HttpRouteState fromContextOrNull(Context context) {
 
   public static void updateSpan(Context context, Span span) {
     HttpRouteState state = fromContextOrNull(context);
-    if (state != null) {
+    if (state != null && state.span == null) {
       state.span = span;
     }
   }

instrumentation-api/src/test/java/io/opentelemetry/instrumentation/api/semconv/http/HttpServerRouteTest.java

@@ -44,7 +44,7 @@ void setUp() {
   }
 
   @Test
-  void noLocalRootSpan() {
+  void nonInstrumenerParentLocalRootSpan() {
     Span parentSpan =
         testing.getOpenTelemetry().getTracer("test").spanBuilder("parent").startSpan();
     parentSpan.end();
@@ -56,10 +56,11 @@ void noLocalRootSpan() {
 
     instrumenter.end(context, "test", null, null);
 
-    assertNull(HttpServerRoute.get(context));
+    assertEquals("/get/:id", HttpServerRoute.get(context));
     assertThat(testing.getSpans())
         .satisfiesExactly(
-            span -> assertThat(span).hasName("parent"), span -> assertThat(span).hasName("test"));
+            span -> assertThat(span).hasName("parent"),
+            span -> assertThat(span).hasName("HTTP /get/:id"));
   }
 
   @Test