public Optional<UncleBlockAdapter> getOmmerAt(final DataFetchingEnvironment environment) {
    final BlockchainQueries query = getBlockchainQueries(environment);
    final int index = ((Number) environment.getArgument("index")).intValue();
    final List<Hash> ommers = blockWithMetaData.getOmmers();
    if (ommers.size() > index) {
      final Hash hash = blockWithMetaData.getHeader().getHash();
      final Optional<BlockHeader> header = query.getOmmer(hash, index);
      return header.map(UncleBlockAdapter::new);
    }
    return Optional.empty();
  }
Returns the ommer at a given index of the block.

@param environment the data fetching environment.
@return an UncleBlockAdapter for the ommer at the given index of the block.
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/graphql/internal/pojoadapter/NormalBlockAdapter.java