fix: proper trace hierarchy — orchestration span as parent of child spans

Start orchestration span BEFORE executor runs so child spans (activities,
timers, client spans) are nested under it. Each dispatch creates its own
orchestration span, matching JS/dotnet behavior (multiple orchestration
spans per trace). Depth is now 3: create_orchestration → orchestration →
activity/timer spans.

Updated all Jaeger and DTS dashboard screenshots.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: torosent

client/src/main/java/com/microsoft/durabletask/DurableTaskGrpcWorker.java

@@ -192,46 +192,47 @@ public void startAndBlock() {
                                     ? startedEvent.getParentTraceContext() : null;
                             String orchName = startedEvent != null ? startedEvent.getName() : "";
 
-                            TaskOrchestratorResult taskOrchestratorResult;
-                            try {
-                                taskOrchestratorResult = taskOrchestrationExecutor.execute(
-                                    orchestratorRequest.getPastEventsList(),
-                                    orchestratorRequest.getNewEventsList(),
-                                    null);
-                            } catch (Throwable e) {
-                                if (e instanceof Error) {
-                                    throw (Error) e;
-                                }
-                                throw new RuntimeException(e);
-                            }
-
-                            // Emit orchestration span only on completion/termination.
-                            // Uses ExecutionStartedEvent timestamp as span start time for full lifecycle coverage.
-                            // Note: Java OTel doesn't support SetSpanId(), so we can't make this span
-                            // the parent of child spans across dispatches like .NET does. Child spans
-                            // (activities, timers) are siblings under the create_orchestration span.
-                            boolean isCompleting = taskOrchestratorResult.getActions().stream()
-                                .anyMatch(a -> a.getOrchestratorActionTypeCase() == OrchestratorAction.OrchestratorActionTypeCase.COMPLETEORCHESTRATION
-                                        || a.getOrchestratorActionTypeCase() == OrchestratorAction.OrchestratorActionTypeCase.TERMINATEORCHESTRATION);
-
-                            if (isCompleting && orchTraceCtx != null) {
+                            // Start the orchestration span BEFORE execution so child spans
+                            // (activities, timers) are nested under it in the trace hierarchy.
+                            // Each dispatch creates its own orchestration span (matching JS/dotnet behavior).
+                            Span orchestrationSpan = null;
+                            TraceContext orchestrationSpanContext = null;
+                            if (orchTraceCtx != null) {
                                 Map<String, String> orchSpanAttrs = new HashMap<>();
                                 orchSpanAttrs.put(TracingHelper.ATTR_TYPE, TracingHelper.TYPE_ORCHESTRATION);
                                 orchSpanAttrs.put(TracingHelper.ATTR_TASK_NAME, orchName);
                                 orchSpanAttrs.put(TracingHelper.ATTR_INSTANCE_ID, orchestratorRequest.getInstanceId());
 
                                 Instant spanStartTime = null;
-                                if (startedHistoryEvent.hasTimestamp()) {
+                                if (startedHistoryEvent != null && startedHistoryEvent.hasTimestamp()) {
                                     spanStartTime = DataConverter.getInstantFromTimestamp(
                                             startedHistoryEvent.getTimestamp());
                                 }
 
-                                Span orchestrationSpan = TracingHelper.startSpanWithStartTime(
+                                orchestrationSpan = TracingHelper.startSpanWithStartTime(
                                         TracingHelper.TYPE_ORCHESTRATION + ":" + orchName,
                                         orchTraceCtx,
                                         SpanKind.SERVER,
                                         orchSpanAttrs,
                                         spanStartTime);
+                                orchestrationSpanContext = TracingHelper.getCurrentTraceContext(orchestrationSpan);
+                            }
+
+                            TaskOrchestratorResult taskOrchestratorResult;
+                            try {
+                                taskOrchestratorResult = taskOrchestrationExecutor.execute(
+                                    orchestratorRequest.getPastEventsList(),
+                                    orchestratorRequest.getNewEventsList(),
+                                    orchestrationSpanContext);
+                            } catch (Throwable e) {
+                                if (e instanceof Error) {
+                                    throw (Error) e;
+                                }
+                                throw new RuntimeException(e);
+                            }
+
+                            // End the orchestration span for every dispatch
+                            if (orchestrationSpan != null) {
                                 orchestrationSpan.end();
                             }