fix compilation error

indexing-service/src/main/java/io/druid/indexing/overlord/setup/FillCapacityWorkerSelectStrategy.java

@@ -47,7 +47,7 @@ public class FillCapacityWorkerSelectStrategy implements WorkerSelectStrategy
     this.config = config;
   }
 
-  public Optional<ZkWorker> findWorkerForTask(
+  public Optional<ImmutableZkWorker> findWorkerForTask(
       final ImmutableMap<String, ImmutableZkWorker> zkWorkers,
       final Task task
   )

indexing-service/src/main/java/io/druid/indexing/worker/Worker.java

@@ -76,7 +76,7 @@ public class Worker
     return "Worker{" +
            "host='" + host + '\'' +
            ", ip='" + ip + '\'' +
-           ", capacity=" + capacity +
+           ",  capacity=" + capacity +
            ", version='" + version + '\'' +
            '}';
   }