Add checkstyle rule to enforce no unused imports.

Quintin Willison · Quintin Willison · commit d7ea99f24862 · 2020-10-01T18:59:13.000+01:00
diff --git a/config/checkstyle/checkstyle.xml b/config/checkstyle/checkstyle.xml
@@ -10,5 +10,6 @@
 
 	<module name="TreeWalker">
 		<module name="RedundantModifier"/>
+		<module name="UnusedImports"/>
 	</module>
 </module>
