docs: public void removeInstalledFeature(String feature) {
          this.configurationError = true;
          HashSet<String> newInstalledFeatures = new HashSet<>(installedFeatures);
          if (newInstalledFeatures.remove(feature)) {
              installedFeatures = newInstalledFeatures.isEmpty() ? Collections.<String> emptySet() : Collections.unmodifiableSet(newInstalledFeatures);
          }
      }