Ensures cronExpression type in WorkflowStarter

Author: SerafimArts

src/Internal/Client/WorkflowStarter.php

@@ -86,7 +86,7 @@ public function start(
             ->setTaskQueue(new TaskQueue(['name' => $options->taskQueue]))
             ->setWorkflowType(new WorkflowType(['name' => $workflowType]))
             ->setWorkflowId($workflowId)
-            ->setCronSchedule($options->cronSchedule)
+            ->setCronSchedule($options->cronSchedule ?? '')
             ->setRetryPolicy($options->toRetryPolicy())
             ->setWorkflowIdReusePolicy($options->workflowIdReusePolicy)
             ->setWorkflowRunTimeout(DateInterval::toDuration($options->workflowRunTimeout))
@@ -152,7 +152,7 @@ public function signalWithStart(
             ->setTaskQueue(new TaskQueue(['name' => $options->taskQueue]))
             ->setWorkflowType(new WorkflowType(['name' => $workflowType]))
             ->setWorkflowId($workflowId)
-            ->setCronSchedule($options->cronSchedule)
+            ->setCronSchedule($options->cronSchedule ?? '')
             ->setRetryPolicy($options->toRetryPolicy())
             ->setWorkflowIdReusePolicy($options->workflowIdReusePolicy)
             ->setWorkflowRunTimeout(DateInterval::toDuration($options->workflowRunTimeout))