Ensure compatibility with RewriteFilterBehavior

Add types and return statements to esnure compatibility with
RewriteFilterbehavior of the modernized ipl-orm.

Author: BastianLedererIcinga

library/Notifications/Model/Behavior/IcingaCustomVars.php

@@ -53,7 +53,7 @@ public function rewriteColumnDefinition(ColumnDefinition $def, string $relation)
         ));
     }
 
-    public function rewriteCondition(Filter\Condition $condition, $relation = null)
+    public function rewriteCondition(Filter\Condition $condition, ?string $relation = null): ?Filter\Condition
     {
         if (! $this->isSelectableColumn($condition->metaData()->get('columnName', ''))) {
             return null;

library/Notifications/Model/Behavior/IdTagAggregator.php

@@ -93,7 +93,8 @@ public function rewriteColumnDefinition(ColumnDefinition $def, string $relation)
     {
     }
 
-    public function rewriteCondition(Filter\Condition $condition, $relation = null)
+    public function rewriteCondition(Filter\Condition $condition, $relation = null): null
     {
+        return null;
     }
 }