PMD: Enable some extra boolean/logic rules

app/src/main/java/org/fdroid/fdroid/AppFilter.java

@@ -29,12 +29,8 @@ public class AppFilter {
             return false;
         }
 
-        if (!Preferences.get().filterAppsRequiringRoot() &&
-                app.requirements.contains("root")) {
-            return true;
-        }
-
-        return false;
+        return !Preferences.get().filterAppsRequiringRoot()
+                && app.requirements.contains("root");
     }
 
 }

config/pmd/rules.xml

@@ -39,4 +39,8 @@
     <rule ref="rulesets/java/design.xml/IdempotentOperations"/>
     <rule ref="rulesets/java/design.xml/ImmutableField"/>
     <rule ref="rulesets/java/design.xml/SingularField"/>
+    <rule ref="rulesets/java/design.xml/SimplifyBooleanReturns"/>
+    <rule ref="rulesets/java/design.xml/SimplifyBooleanExpressions"/>
+    <rule ref="rulesets/java/design.xml/LogicInversion"/>
+
 </ruleset>