code: @Override
    public Set<RepositoryCapability> getCapabilities() {
      Set<RepositoryCapability> capabilities = new HashSet<>();
      capabilities.addAll(delegate().getCapabilities());
      capabilities.addAll(EnumSet.of(QUERYABLE, AGGREGATEABLE));
      return unmodifiableSet(capabilities);
    }
docs: Gets the capabilities of the underlying repository and adds three read capabilities provided by
  the index: {@link RepositoryCapability#INDEXABLE}, {@link RepositoryCapability#QUERYABLE} and
  {@link RepositoryCapability#AGGREGATEABLE}. Does not add other index capabilities like{@link
  RepositoryCapability#WRITABLE} because those might conflict with the underlying repository.