code: private boolean isMember(IGroupMember groupMember, String groupName) {
          try {
              IEntityGroup group = GroupService.findGroup(groupName);
              if (group != null) {
                  return groupMember.isDeepMemberOf(group);
              }
  
              final EntityIdentifier[] results =
                      GroupService.searchForGroups(
                              groupName, GroupService.SearchMethod.DISCRETE, IPerson.class);
              if (results == null || results.length == 0) {
                  this.logger.warn(
                          "No portal group found for '{}' no users will be placed in that group for analytics",
                          groupName);
                  return false;
              }
  
              if (results.length > 1) {
                  this.logger.warn(
                          "{} groups were found for groupName '{}'. The first result will be used.",
                          results.length,
                          groupName);
              }
  
              group = (IEntityGroup) GroupService.getGroupMember(results[0]);
              return groupMember.isDeepMemberOf(group);
          } catch (Exception e) {
              this.logger.warn(
                      "Failed to determine if {} is a member of {}, returning false",
                      groupMember,
                      groupName,
                      e);
              return false;
          }
      }
docs: Check if the user is a member of the specified group name
  
  <p>Internal search, thus case sensitive.