@Override
  public short readShort() {
    checkElt("2-byte short", 2);
    final short s = (short) ((payloadByte(0) << 8) | (payloadByte(1) & 0xFF));
    setTo(nextItem());
    return s;
  }
Sets the input to the item provided (an offset to the beginning of an item) and check this is
valid.

@param item the value to which the current item is to be set.
ethereum/rlp/src/main/java/org/hyperledger/besu/ethereum/rlp/AbstractRLPInput.java