code: public ManagementVertex getGroupMember(final int index) {
  
  		if (index < this.groupMembers.size()) {
  			return this.groupMembers.get(index);
  		}
  
  		return null;
  	}
docs: Returns the management vertex with the given index.
  
  @param index
  the index of the management vertex to be returned
  @return the management vertex with the given index or <code>null</code> if no such vertex exists