code: public ExtensionFeatureOptions withDependency(ExtensionFeature feature) {
          Set<String> existing = this.dependencies;
          Set<String> newDependencies;
          if (existing == null) {
              newDependencies = new HashSet<>();
          } else {
              newDependencies = new HashSet<>(existing);
          }
          newDependencies.add(feature.getId());
          return withDependencies(newDependencies);
      }
docs: Adds a dependency