presto-main/src/main/java/io/prestosql/operator/aggregation/KeyValuePairs.java/KeyValuePairs/getHashPositionOfKey
class KeyValuePairs:    private int getHashPositionOfKey(Block key, int position)
    {
        int hashPosition = getMaskedHash(hashPosition(keyType, key, position));
        while (true) {
            if (keyPositionByHash[hashPosition] == EMPTY_SLOT) {
                return hashPosition;
            }
            if (positionEqualsPosition(keyType, keyBlockBuilder, keyPositionByHash[hashPosition], key, position)) {
                return hashPosition;
            }
            hashPosition = getMaskedHash(hashPosition + 1);
        }
    }