public static GetBlockHeadersData create(
        final Hash hash, final int maxHeaders, final int skip, final boolean reverse) {
      return new GetBlockHeadersData(
          Optional.of(hash), OptionalLong.empty(), maxHeaders, skip, reverse);
    }
Returns the block hash that the message requests or {@link Optional#empty()} if the request
specifies a block number.

@return Block Hash Requested or {@link Optional#empty()}
ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/messages/GetBlockHeadersMessage.java