public static @NotNull <T extends PsiElement> T getRequiredChildOfType(@NotNull PsiElement element, @NotNull Class<T> aClass) {
    T child = getChildOfType(element, aClass);
    assert child != null : "Missing required child of type " + aClass.getName();
    return child;
  }
public static @NotNull <T extends PsiElement> T getRequiredChildOfType(@NotNull PsiElement element, @NotNull Class<T> aClass)