HADOOP-17897. Allow nested blocks in switch case in checkstyle settings. (#3394)

Author: iwasakims

hadoop-build-tools/src/main/resources/checkstyle/checkstyle.xml

@@ -160,7 +160,9 @@
 
         <!-- Checks for blocks. You know, those {}'s         -->
         <!-- See http://checkstyle.sf.net/config_blocks.html -->
-        <module name="AvoidNestedBlocks"/>
+        <module name="AvoidNestedBlocks">
+          <property name="allowInSwitchCase" value="true"/>
+        </module>
         <module name="EmptyBlock"/>
         <module name="LeftCurly"/>
         <module name="NeedBraces"/>