code: public V findChachedValueOf(K key) {
  
  		// check selection
  		for (V value : selection) {
  			if (getKeyOf(value).equals(key)) {
  				return value;
  			}
  		}
  
  		// check data cache
  		for (V value : getData()) {
  			if (getKeyOf(value).equals(key)) {
  				return value;
  			}
  		}
  
  		return null;
  	}
docs: Find value in cached data.
  
  @param key
  @return found value or null if non was found