@Override
        public @NotNull Collection<String> getItems(String prefix, boolean cached, CompletionParameters parameters) {
            return DumbService.isDumb(getProject())
                   ? List.of()
                   : ReadAction.compute(() -> StubIndex.getInstance().getAllKeys(JavaStubIndexKeys.IMPLICIT_CLASSES, getProject()));
        }
@Override
        public @NotNull Collection<String> getItems(String prefix, boolean cached, CompletionParameters parameters)