code: public boolean checkUser(String globusID, String userID) {
          if (globusID == null) {
              throw new IllegalArgumentException(i18n.getMessage("glousIdNull"));
          }
          if (userID == null) {
              throw new IllegalArgumentException(i18n.getMessage("userIdNull"));
          }
  
          if (this.map == null) {
              return false;
          }
  
          GridMapEntry entry = (GridMapEntry)this.map.get(normalizeDN(globusID));
          return (entry == null) ? false : entry.containsUserID(userID);
      }
docs: Checks if a given globus ID is associated with given
  local user account.
  
  @param globusID globus ID
  @param userID userID
  @return true if globus ID is associated with given local
  user account, false, otherwise.