code: protected void addCacheKeyGenerators(
  			Map<String, ICacheKeyGenerator> cacheKeyGenerators,
  			Iterable<ICacheKeyGenerator> gens)
  	{
  		if (gens != null) {
  			for (ICacheKeyGenerator gen : gens) {
  				String className = gen.getClass().getName();
  				ICacheKeyGenerator current = cacheKeyGenerators.get(className);
  				cacheKeyGenerators.put(className,
  						(current == null) ? gen : current.combine(gen));
  			}
  		}
  	}
docs: Adds the cache key generators specified in {@code gens} to the map of
  classname/key-generator pairs, combining key-generators as needed.
  
  @param cacheKeyGenerators
  Map of classname/key-generator pairs to add to.
  @param gens
  the cache key generators to add.