stream API collect method compiler error - Object cannot be cast to List

I cannot see what the problem is with my stream api logic. It tells me the following

[ERROR] mystuff/MandantContentFetcher.java:[67,23] incompatible types: java.lang.Object cannot be converted to java.util.List

this is my stream method:

static List<MandantLinkCheckerEntry> createMandantLinkCheckerEntries(Struct struct) {
    Map<String, Object> linkCheckerMandants = struct.toNestedMaps();
    return linkCheckerMandants.values().parallelStream()
            .map(Map.class::cast)
            .map(MandantLinkCheckerEntry::convertMapToMandantCheckerEntry)
            .collect(Collectors.toList());
  }

which uses this method reference:

  private static MandantLinkCheckerEntry convertMapToMandantCheckerEntry(Map<String, Object> entryToConvert) {
    return new MandantLinkCheckerEntry(String.valueOf(entryToConvert.get("mandant.path")),
            String.valueOf(entryToConvert.get("mail.to")),
            Boolean.valueOf(String.valueOf(entryToConvert.get("active"))));
  }

Why does he see a Object? The method reference in the 2nd map does return a MandantLinkCheckerEntry. Also I assume collect does create a List with the streamed values as generic type but it seems that he converts the type of the stream (which is Object here as the Stream initiator is Map<String, Object). How can I help him cast this to a List?