private void calculatePrivateMethodUsagesIfNecessary() {
    if (privateMethodUsagesCalculated) {
      return;
    }
    final Set<PsiMethod> privateMethods = findPrivateMethods();
    final HashMap<PsiMethod, Collection<PsiReference>> referenceMap =
      buildReferenceMap(privateMethods);
    determineUsedMethods(privateMethods, referenceMap);
    determineUsageMap(referenceMap);
    privateMethodUsagesCalculated = true;
  }
private void calculatePrivateMethodUsagesIfNecessary()