Fix minor issues

Author: RanVaknin

core/aws-core/src/main/java/software/amazon/awssdk/awscore/interceptor/TraceIdExecutionInterceptor.java

@@ -70,7 +70,10 @@ public void onExecutionFailure(Context.FailedExecution context, ExecutionAttribu
     }
 
     private static void saveTraceId(ExecutionAttributes executionAttributes) {
-        MDC.put(CONCURRENT_TRACE_ID_KEY, executionAttributes.getAttribute(TRACE_ID));
+        String traceId = executionAttributes.getAttribute(TRACE_ID);
+        if (traceId != null) {
+            MDC.put(CONCURRENT_TRACE_ID_KEY, executionAttributes.getAttribute(TRACE_ID));
+        }
     }
 
     private Optional<String> traceIdHeader(Context.ModifyHttpRequest context) {

test/codegen-generated-classes-test/src/test/java/software/amazon/awssdk/services/TraceIdTest.java

@@ -37,8 +37,7 @@
 /**
  * Verifies that the {@link TraceIdExecutionInterceptor} is actually wired up for AWS services.
  */
-public class
-TraceIdTest {
+public class TraceIdTest {
     @Test
     public void traceIdInterceptorIsEnabled() {
         EnvironmentVariableHelper.run(env -> {
@@ -130,7 +129,6 @@ public void traceIdInterceptorPreservesTraceIdAcrossChainedFutures() {
 
                 client.allTypes()
                       .thenRun(() -> {
-                          String traceId = MDC.get("AWS_LAMBDA_X_TRACE_ID");
                           client.allTypes().join();
                       })
                       .join();