docs: public ApiResponse<List<MailHeadersResponse>> getCharactersCharacterIdMailWithHttpInfo(Integer characterId,
              String datasource, String ifNoneMatch, List<Integer> labels, Integer lastMailId, String token)
              throws ApiException {
          com.squareup.okhttp.Call call = getCharactersCharacterIdMailValidateBeforeCall(characterId, datasource,
                  ifNoneMatch, labels, lastMailId, token, null);
          Type localVarReturnType = new TypeToken<List<MailHeadersResponse>>() {
          }.getType();
          return apiClient.execute(call, localVarReturnType);
      }