fix(tracing): record CancellationException on lingering attempt when superseded by retry

Author: jinseopkim0

sdk-platform-java/gax-java/gax/src/main/java/com/google/api/gax/tracing/OpenTelemetryTracingTracer.java

@@ -243,7 +243,7 @@ public void attemptStarted(Object request, int attemptNumber) {
     }
     // End lingering previous attempt outside the lock to avoid holding the lock during callbacks.
     if (oldSpan != null) {
-      endSpan(oldSpan, null);
+      endSpan(oldSpan, new CancellationException("Attempt superseded by retry"));
     }
   }
 

sdk-platform-java/gax-java/gax/src/test/java/com/google/api/gax/tracing/OpenTelemetryTracingTracerTest.java

@@ -799,6 +799,8 @@ void testAttemptStarted_whenPreviousAttemptActive_closesOldSpan() {
 
     // Start a second attempt before the first attempt was ended
     openTelemetryTracingTracer.attemptStarted(new Object(), 1);
+    verify(span1).recordException(any(java.util.concurrent.CancellationException.class));
+    verify(span1).setStatus(io.opentelemetry.api.trace.StatusCode.ERROR);
     verify(span1).end();
     verify(span2, never()).end();