Update checkstyle config

- allow empty block, as long as there's some comment

Change-Id: Idbaf727220dc9b2d301dfa19a8d3e185b1a865cd
diff --git a/tools/build/conf/src/main/resources/onos/checkstyle.xml b/tools/build/conf/src/main/resources/onos/checkstyle.xml
index 2908c89..1bb3b0b 100644
--- a/tools/build/conf/src/main/resources/onos/checkstyle.xml
+++ b/tools/build/conf/src/main/resources/onos/checkstyle.xml
@@ -229,7 +229,10 @@
             <!-- ONOS alows declarations inside of switch case blocks -->
             <property name="allowInSwitchCase" value="true"/>
         </module>
-        <module name="EmptyBlock"/>
+        <module name="EmptyBlock">
+            <!-- allow empty block, as long as there's some comment -->
+            <property name="option" value="text"/>
+        </module>
         <module name="LeftCurly"/>
         <module name="NeedBraces"/>
         <module name="RightCurly"/>