move tip to interface

Author: halibobo1205

framework/src/main/java/org/tron/common/application/Application.java

@@ -34,6 +34,7 @@ public interface Application {
 
   void startServices();
 
+  // DO NOT USE THIS METHOD IN TEST CASES MAIN-THREAD
   default void blockUntilShutdown() {
   }
 

framework/src/main/java/org/tron/common/application/ApplicationImpl.java

@@ -79,7 +79,6 @@ public void startServices() {
   }
 
   @Override
-  // DO NOT USE THIS METHOD IN TEST CASES
   public void blockUntilShutdown() {
     services.blockUntilShutdown();
   }