code: public List<Chain> getChains(){
  		ArrayList<Chain> chains = new ArrayList<>();
  
  		chains.addAll(polyChains);
  		chains.addAll(nonPolyChains);
  		chains.addAll(waterChains);
  
  		chains.trimToSize();
  
  		return chains;
  	}
docs: Get all chains: polymeric, non-polymeric and water
  @return