Respond to PR comments

Author: Quinn-With-Two-Ns

temporal-sdk/src/main/java/io/temporal/internal/common/InternalUtils.java

@@ -86,8 +86,7 @@ public static NexusWorkflowStarter createNexusBoundStub(
     } catch (JsonProcessingException e) {
       // Not expected as the link is constructed by the SDK.
       throw new HandlerException(
-          HandlerException.ErrorType.BAD_REQUEST,
-          new IllegalArgumentException("failed to generate workflow operation token", e));
+          HandlerException.ErrorType.BAD_REQUEST, "failed to generate workflow operation token", e);
     }
     List<Link> links =
         request.getLinks() == null

temporal-sdk/src/main/java/io/temporal/internal/common/NexusUtil.java

@@ -60,7 +60,9 @@ public static Failure temporalFailureToNexusFailure(
       io.temporal.api.failure.v1.Failure temporalFailure) {
     String details;
     try {
-      details = PROTO_JSON_PRINTER.print(temporalFailure.toBuilder().setMessage("").build());
+      details =
+          PROTO_JSON_PRINTER.print(
+              temporalFailure.toBuilder().setMessage("").setStackTrace("").build());
     } catch (InvalidProtocolBufferException e) {
       return Failure.newBuilder()
           .setMessage("Failed to serialize failure details")
@@ -138,7 +140,9 @@ public static FailureInfo temporalFailureToNexusFailureInfo(
       io.temporal.api.failure.v1.Failure temporalFailure) {
     String details;
     try {
-      details = PROTO_JSON_PRINTER.print(temporalFailure.toBuilder().setMessage("").build());
+      details =
+          PROTO_JSON_PRINTER.print(
+              temporalFailure.toBuilder().setMessage("").setStackTrace("").build());
     } catch (InvalidProtocolBufferException e) {
       return FailureInfo.newBuilder()
           .setMessage("Failed to serialize failure details")
@@ -157,18 +161,23 @@ public static Failure exceptionToNexusFailure(Throwable exception, DataConverter
     return temporalFailureToNexusFailure(failure);
   }
 
+  /**
+   * Convert a HandlerException to the legacy HandlerError format used by Nexus, including
+   * converting the cause to a Failure.
+   */
   public static HandlerError handlerErrorToNexusError(
       HandlerException e, DataConverter dataConverter) {
     HandlerError.Builder handlerError =
         HandlerError.newBuilder()
             .setErrorType(e.getErrorType().toString())
             .setRetryBehavior(mapRetryBehavior(e.getRetryBehavior()));
-    // TODO: check if this works on old server
     if (e.getCause() != null) {
       handlerError.setFailure(exceptionToNexusFailure(e.getCause(), dataConverter));
     } else if (e.getMessage() != null && !e.getMessage().isEmpty()) {
-      // Include message even when there's no cause
-      handlerError.setFailure(Failure.newBuilder().setMessage(e.getMessage()).build());
+      // Generate a failure from the message if no cause is provided, to ensure the error is not
+      // empty
+      handlerError.setFailure(
+          exceptionToNexusFailure(new RuntimeException(e.getMessage()), dataConverter));
     }
     return handlerError.build();
   }

temporal-sdk/src/main/java/io/temporal/internal/nexus/NexusTaskHandlerImpl.java

@@ -105,8 +105,7 @@ public Result handle(NexusTask task, Scope metricsScope) throws TimeoutException
                   java.util.concurrent.TimeUnit.MILLISECONDS);
         } catch (IllegalArgumentException e) {
           throw new HandlerException(
-              HandlerException.ErrorType.BAD_REQUEST,
-              new RuntimeException("Invalid request timeout header", e));
+              HandlerException.ErrorType.BAD_REQUEST, "Invalid request timeout header", e);
         }
       }
 
@@ -125,12 +124,14 @@ public Result handle(NexusTask task, Scope metricsScope) throws TimeoutException
         default:
           throw new HandlerException(
               HandlerException.ErrorType.NOT_IMPLEMENTED,
-              new RuntimeException("Unknown request type: " + request.getVariantCase()));
+              "Unknown request type: " + request.getVariantCase(),
+              (Throwable) null);
       }
     } catch (HandlerException e) {
       return new Result(e);
     } catch (Throwable e) {
-      return new Result(new HandlerException(HandlerException.ErrorType.INTERNAL, e));
+      return new Result(
+          new HandlerException(HandlerException.ErrorType.INTERNAL, "internal handler error", e));
     } finally {
       // If the task timed out, we should not send a response back to the server
       if (timedOut.get()) {
@@ -285,7 +286,8 @@ private StartOperationResponse handleStartOperation(
                 log.error("failed to parse link url: " + link.getUrl(), e);
                 throw new HandlerException(
                     HandlerException.ErrorType.BAD_REQUEST,
-                    new RuntimeException("Invalid link URL: " + link.getUrl(), e));
+                    "Invalid link URL: " + link.getUrl(),
+                    e);
               }
             });
 

temporal-sdk/src/main/java/io/temporal/nexus/WorkflowRunOperationImpl.java

@@ -68,9 +68,7 @@ public OperationStartResult<R> start(
         ctx.addLinks(nexusProtoLinkToLink(nexusLink));
       } catch (URISyntaxException e) {
         // Not expected as the link is constructed by the SDK.
-        throw new HandlerException(
-            HandlerException.ErrorType.INTERNAL,
-            new IllegalArgumentException("failed to parse URI", e));
+        throw new HandlerException(HandlerException.ErrorType.INTERNAL, "failed to parse URI", e);
       }
     }
     return result.build();
@@ -86,8 +84,7 @@ public void cancel(
               operationCancelDetails.getOperationToken());
     } catch (IllegalArgumentException e) {
       throw new HandlerException(
-          HandlerException.ErrorType.BAD_REQUEST,
-          new IllegalArgumentException("failed to parse operation token", e));
+          HandlerException.ErrorType.BAD_REQUEST, "failed to parse operation token", e);
     }
 
     WorkflowClient client = CurrentNexusOperationContext.get().getWorkflowClient();