Added missing override annotations

Plan/src/main/java/com/djrapitops/plan/Plan.java

@@ -161,6 +161,7 @@ public class Plan extends BukkitPlugin implements PlanPlugin {
         throw new IllegalStateException("This method should be used on this plugin.");
     }
 
+    @Override
     public BukkitSystem getSystem() {
         return system;
     }

Plan/src/main/java/com/djrapitops/plan/PlanBungee.java

@@ -93,6 +93,7 @@ public class PlanBungee extends BungeePlugin implements PlanPlugin {
         return PlanColorScheme.create();
     }
 
+    @Override
     public BungeeSystem getSystem() {
         return system;
     }

Plan/src/main/java/com/djrapitops/plan/PlanSponge.java

@@ -124,6 +124,7 @@ public class PlanSponge extends SpongePlugin implements PlanPlugin {
         return getClass().getAnnotation(Plugin.class).version();
     }
 
+    @Override
     public SpongeSystem getSystem() {
         return system;
     }

Plan/src/main/java/com/djrapitops/plan/data/store/mutators/health/HealthInformation.java

@@ -38,6 +38,7 @@ public class HealthInformation extends AbstractHealthInfo {
         calculate();
     }
 
+    @Override
     public String toHtml() {
         StringBuilder healthNoteBuilder = new StringBuilder();
         for (String healthNote : notes) {