public Optional<Integer> getOmmerCount(final long blockNumber) {
    return blockchain.getBlockHashByNumber(blockNumber).flatMap(this::getOmmerCount);
  }
Returns the number of ommers in the block at the given height.

@param blockNumber The height of the block being queried.
@return The number of ommers in the referenced block.
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/query/BlockchainQueries.java