docs: public List<MailHeadersResponse> getCharactersCharacterIdMail(Integer characterId, String datasource,
              String ifNoneMatch, List<Integer> labels, Integer lastMailId, String token) throws ApiException {
          ApiResponse<List<MailHeadersResponse>> resp = getCharactersCharacterIdMailWithHttpInfo(characterId, datasource,
                  ifNoneMatch, labels, lastMailId, token);
          return resp.getData();
      }