code: public void addGroup(Group section) {
      if (section != null) {
        if (section.isAnyAgent()) {
          if (this.defaultSection == null) {
            this.defaultSection = section;
          } else {
            this.defaultSection.getAccessList().importAccess(section.getAccessList());
          }
        } else {
          Group exact = findExactSection(section);
          if (exact == null) {
            groups.add(section);
          } else {
            exact.getAccessList().importAccess(section.getAccessList());
          }
        }
      }
    }
docs: Adds section.
  
  @param section section