Avoid direct casting of base service tag to string (#9489)

Author: amarziali

dd-trace-core/src/main/java/datadog/trace/common/metrics/ConflatingMetricsAggregator.java

@@ -367,12 +367,14 @@ private List<UTF8BytesString> getPeerTags(CoreSpan<?> span, String spanKind) {
       return peerTags;
     } else if (SPAN_KIND_INTERNAL.equals(spanKind)) {
       // in this case only the base service should be aggregated if present
-      final String baseService = span.getTag(BASE_SERVICE);
+      final Object baseService = span.getTag(BASE_SERVICE);
       if (baseService != null) {
         final Pair<DDCache<String, UTF8BytesString>, Function<String, UTF8BytesString>>
             cacheAndCreator = PEER_TAGS_CACHE.computeIfAbsent(BASE_SERVICE, PEER_TAGS_CACHE_ADDER);
         return Collections.singletonList(
-            cacheAndCreator.getLeft().computeIfAbsent(baseService, cacheAndCreator.getRight()));
+            cacheAndCreator
+                .getLeft()
+                .computeIfAbsent(baseService.toString(), cacheAndCreator.getRight()));
       }
     }
     return Collections.emptyList();

dd-trace-core/src/test/groovy/datadog/trace/common/metrics/ConflatingMetricAggregatorTest.groovy

@@ -263,7 +263,7 @@ class ConflatingMetricAggregatorTest extends DDSpecification {
     CountDownLatch latch = new CountDownLatch(1)
     aggregator.publish([
       new SimpleSpan("service", "operation", "resource", "type", true, false, false, 0, 100, HTTP_OK)
-      .setTag(SPAN_KIND, kind).setTag("peer.hostname", "localhost").setTag("_dd.base_service", "test")
+      .setTag(SPAN_KIND, kind).setTag("peer.hostname", "localhost").setTag("_dd.base_service", UTF8BytesString.create("test"))
     ])
     aggregator.report()
     def latchTriggered = latch.await(2, SECONDS)