code: public static Defaultable<Boolean> ifAllExplicitlySet(Defaultable<?>... items) {
          return bool(() -> {
              for (Defaultable<?> item : items) {
                  if (!item.isExplicit()) {
                      return false;
                  }
              }
              return true;
          });
      }
docs: Create a <code>Boolean</code> configuration that has a default value of <code>true</code> if all arguments have been explicitly set to non-default values.
  
  @param items The items to test.
  @return The new item.