Fix NPE

Signed-off-by: siri-varma <siri.varma@outlook.com>
Signed-off-by: sirivarma <siri.varma@outlook.com>

Author: siri-varma

examples/src/main/java/io/dapr/examples/workflows/childworkflow/DemoChildWorkflowWorker.java

@@ -13,13 +13,9 @@
 
 package io.dapr.examples.workflows.childworkflow;
 
-import io.dapr.workflows.WorkflowTaskRetryPolicy;
 import io.dapr.workflows.runtime.WorkflowRuntime;
 import io.dapr.workflows.runtime.WorkflowRuntimeBuilder;
 
-import java.time.Duration;
-import java.time.temporal.ChronoUnit;
-
 public class DemoChildWorkflowWorker {
   /**
    * The main method of this app.