simple-ui: fix NPE on filters

Author: zeapo

hawkbit-simple-ui/src/main/java/org/eclipse/hawkbit/ui/simple/view/util/Filter.java

@@ -15,7 +15,6 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.function.Consumer;
-import java.util.function.Predicate;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;