code: public Map<String, Timestamp> getUserContributionMap(final int articleID, String[] groupfilter)
          throws WikiApiException
      {
          return getUserContributionMap(articleID, groupfilter, false);
      }
docs: Returns a map of usernames mapped to the timestamps of their contributions.
  
  Users of certain user groups (e.g. bots) can be filtered by providing the unwanted groups in
  the {@code groupFilter}. Nothing is filtered if the {@code groupFilter} is {@code null} or empty.<br>
  <br>
  Filtered results also include unregistered users (because they cannot be filtered using user
  groups) In order to get results containing only registered users, use {@link
  #getUserContributionMap(int, String[], boolean)} and set {@code onlyRegistered=true}.<br>
  <br>
  In order to make this query fast, create a MySQL-Index (BTREE) on the ArticleID in the
  revisions-table.
  
  @param articleID
  ID of the article
  @param groupfilter
  a list of unwanted user groups
  @return map of Timestamp-DiffPart-Collection pairs
  
  @throws WikiApiException
  if an error occurs