PMD: Enable and obey UnnecessaryConstructor

app/src/main/java/org/fdroid/fdroid/localrepo/SwapService.java

@@ -91,10 +91,6 @@ public class SwapService extends Service {
     @NonNull
     private final Set<String> appsToSwap = new HashSet<>();
 
-    public SwapService() {
-        super();
-    }
-
     /**
      * Where relevant, the state of the swap process will be saved to disk using preferences.
      * Note that this is not always useful, for example saving the "current wifi network" is

config/pmd/rules.xml

@@ -17,4 +17,5 @@
     </rule>
     <rule ref="rulesets/java/optimizations.xml/PrematureDeclaration"/>
     <rule ref="rulesets/java/optimizations.xml/AddEmptyString"/>
+    <rule ref="rulesets/java/controversial.xml/UnnecessaryConstructor"/>
 </ruleset>