Update dd-java-agent/instrumentation/kafka/kafka-clients-3.8/src/main/java17/datadog/trace/instrumentation/kafka_clients38/TracingIterator.java

Co-authored-by: Stuart McCulloch <stuart.mcculloch@datadoghq.com>

Author: amarziali

dd-java-agent/instrumentation/kafka/kafka-clients-3.8/src/main/java17/datadog/trace/instrumentation/kafka_clients38/TracingIterator.java

@@ -87,7 +87,7 @@ protected void startNewRecordSpan(ConsumerRecord<?, ?> val) {
     try {
       if (InstrumenterConfig.get().isLegacyContextManagerEnabled()) {
         closePrevious(true);
-      } else {
+      } else if (val == null) { // previous message span was the last
         final AgentSpan previousSpan = spanFromContext(getRootContext().swap());
         if (previousSpan != null) {
           previousSpan.finishWithEndToEnd();