Enable checkstyle rule to check for redundant throws

Enable the checkstyle "RedundantThrows" check and fix any
violations.  This rule checks that methods don't throw
Exceptions that are subclasses of exceptions that have
already been thrown.

Change-Id: Ib5865a9dea8551de105ec13abbf4c61659da9330
diff --git a/conf/checkstyle/sun_checks.xml b/conf/checkstyle/sun_checks.xml
index 47121a6..3d0ccb1 100644
--- a/conf/checkstyle/sun_checks.xml
+++ b/conf/checkstyle/sun_checks.xml
@@ -216,8 +216,8 @@
         </module>
 
         <module name="RedundantThrows">
-          <property name="severity" value="warning"/>
-        </module>
+	   <property name="allowSubclasses" value="true"/>
+	</module>
 
         <module name="SimplifyBooleanExpression"/>
         <module name="SimplifyBooleanReturn"/>