changed from synchronizedMap to Map, as synchronization is not needed in workflow code

Author: antmendoza

core/src/main/java/io/temporal/samples/taskinteraction/TaskService.java

@@ -32,7 +32,7 @@
 
 public class TaskService<R> {
 
-  private final Map<String, Task> tasks = Collections.synchronizedMap(new HashMap<>());
+  private final Map<String, Task> tasks = new HashMap<>();
   private final Map<String, CompletablePromise<R>> pendingPromises =
       Collections.synchronizedMap(new HashMap<>());