private Map<String, Hybridization> getIdToHybridizationMap() throws InvalidInputException {
   if (idToHybridizationMap == null) {
     idToHybridizationMap = new HashMap<String, Hybridization>();
     for (Hybridization hybridization : getAllHybridizations()) {
       idToHybridizationMap.put(hybridization.getId(), hybridization);
     }
   }
   return idToHybridizationMap;
 }
 protected Sample getAssociatedSample(Hybridization hybridization) throws InvalidInputException {
   return getHybridizationToSampleMap().get(getIdToHybridizationMap().get(hybridization.getId()));
 }