Fix test server nexus failure wrapping and test assertions for server 1.31.0

- Update nexusFailureToAPIFailure to not wrap non-temporal failures in
  ApplicationFailureInfo (matching real server behavior)
- Update handlerErrorToFailure to not set message at top level (message
  is only in the nested cause on real server)
- Update NexusWorkflowTest assertions to check cause.getCause() for
  handler error messages
- Remove applicationFailureInfo assertion from testNexusOperationError
- Skip testNexusOperationTimeout_AfterCancel with real server (timeout
  behavior after cancel differs)
- Skip testNexusOperationScheduleToStartTimeout with real server
  (requires time skipping)
- Skip WorkflowIdConflictPolicyTest.conflictPolicyUseExisting with real
  server (callback URL validation rejects test URLs)

Author: bergundy

temporal-test-server/src/main/java/io/temporal/internal/testservice/TestWorkflowService.java

@@ -1171,7 +1171,6 @@ public void completeNexusOperation(
 
   private static Failure handlerErrorToFailure(HandlerError err) {
     return Failure.newBuilder()
-        .setMessage(err.getFailure().getMessage())
         .setNexusHandlerFailureInfo(
             NexusHandlerFailureInfo.newBuilder()
                 .setType(err.getErrorType())
@@ -1196,13 +1195,6 @@ private static Failure nexusFailureToAPIFailure(
       } catch (InvalidProtocolBufferException e) {
         throw new RuntimeException(e);
       }
-    } else {
-      Payloads payloads = nexusFailureMetadataToPayloads(failure);
-      ApplicationFailureInfo.Builder applicationFailureInfo = ApplicationFailureInfo.newBuilder();
-      applicationFailureInfo.setType("NexusFailure");
-      applicationFailureInfo.setDetails(payloads);
-      applicationFailureInfo.setNonRetryable(!retryable);
-      apiFailure.setApplicationFailureInfo(applicationFailureInfo.build());
     }
     apiFailure.setMessage(failure.getMessage());
     return apiFailure.build();

temporal-test-server/src/test/java/io/temporal/testserver/functional/NexusWorkflowTest.java

@@ -630,6 +630,9 @@ public void testNexusOperationTimeout_AfterStart() {
 
   @Test(timeout = 30000)
   public void testNexusOperationTimeout_AfterCancel() {
+    assumeTrue(
+        "Skipping for real server: timeout behavior after cancel differs",
+        !testWorkflowRule.isUseExternalService());
     String operationId = UUID.randomUUID().toString();
     CompletableFuture<?> nexusPoller =
         pollNexusTask().thenCompose(task -> completeNexusTask(task, operationId));
@@ -712,6 +715,9 @@ public void testNexusOperationTimeout_AfterCancel() {
 
   @Test
   public void testNexusOperationScheduleToStartTimeout() {
+    assumeTrue(
+        "Skipping for real server: schedule-to-start timeout requires time skipping",
+        !testWorkflowRule.isUseExternalService());
     WorkflowStub stub = newWorkflowStub("TestNexusOperationScheduleToStartTimeoutWorkflow");
     WorkflowExecution execution = stub.start();
 
@@ -885,8 +891,6 @@ public void testNexusOperationError() {
       Assert.assertEquals("nexus operation completed unsuccessfully", failure.getMessage());
       io.temporal.api.failure.v1.Failure cause = failure.getCause();
       Assert.assertEquals("deliberate test failure", cause.getMessage());
-      Assert.assertTrue(cause.hasApplicationFailureInfo());
-      Assert.assertEquals("NexusFailure", cause.getApplicationFailureInfo().getType());
     } catch (Exception e) {
       Assert.fail(e.getMessage());
     } finally {
@@ -947,9 +951,9 @@ public void testNexusOperationHandlerError() {
       assertOperationFailureInfo(failure.getNexusOperationExecutionFailureInfo());
       Assert.assertEquals("nexus operation completed unsuccessfully", failure.getMessage());
       io.temporal.api.failure.v1.Failure cause = failure.getCause();
-      Assert.assertTrue(cause.getMessage().endsWith("deliberate terminal error"));
       Assert.assertTrue(cause.hasNexusHandlerFailureInfo());
       Assert.assertEquals("BAD_REQUEST", cause.getNexusHandlerFailureInfo().getType());
+      Assert.assertEquals("deliberate terminal error", cause.getCause().getMessage());
     } catch (Exception e) {
       Assert.fail(e.getMessage());
     } finally {
@@ -1016,9 +1020,9 @@ public void testNexusOperationHandlerTemporalFailure() {
       assertOperationFailureInfo(failure.getNexusOperationExecutionFailureInfo());
       Assert.assertEquals("nexus operation completed unsuccessfully", failure.getMessage());
       io.temporal.api.failure.v1.Failure cause = failure.getCause();
-      Assert.assertTrue(cause.getMessage().endsWith("deliberate terminal error"));
       Assert.assertTrue(cause.hasNexusHandlerFailureInfo());
       Assert.assertEquals("BAD_REQUEST", cause.getNexusHandlerFailureInfo().getType());
+      Assert.assertEquals("deliberate terminal error", cause.getCause().getMessage());
     } catch (Exception e) {
       Assert.fail(e.getMessage());
     } finally {

temporal-test-server/src/test/java/io/temporal/testserver/functional/WorkflowIdConflictPolicyTest.java

@@ -41,6 +41,9 @@ public class WorkflowIdConflictPolicyTest {
 
   @Test
   public void conflictPolicyUseExisting() {
+    org.junit.Assume.assumeTrue(
+        "Skipping for real server: callback URL validation rejects test URLs",
+        !testWorkflowRule.isUseExternalService());
     String workflowId = "conflict-policy-use-existing";
     String requestId = randomUUID().toString();