code: public List<String> getChainIds() {
  
  		Set<String> uniqChainIds = new TreeSet<>();
  		for (int i=0;i<getChains().size();i++) {
  			uniqChainIds.add(getChains().get(i).getId());
  		}
  
  		return new ArrayList<>(uniqChainIds);
  	}
docs: Return the list of member chain ids (asym ids) that are described by this EntityInfo,
  only unique chain IDs are contained in the list.
  Note that in the case of multimodel structures this will return just the unique
  chain identifiers whilst {@link #getChains()} will return a corresponding chain
  per model.
  @return the list of unique ChainIDs that are described by this EnityInfo
  @see #setChains(List)
  @see #getChains()