@Nullable
  private static PsiType getGenericElementType(PsiType collectionType) {
    if (collectionType instanceof PsiClassType classType) {
      PsiType[] parameters = classType.getParameters();
      if (parameters.length == 1) {
        return parameters[0];
      }
    }
    return null;
  }
@Nullable
  private static PsiType getGenericElementType(PsiType collectionType)