presto-spi/src/main/java/io/prestosql/spi/block/MapHashTables.java/MapHashTables/getHashPosition
class MapHashTables:    private int getHashPosition(Block keyBlock, int position, int hashTableSize)
    {
        if (keyBlock.isNull(position)) {
            throw new IllegalArgumentException("map keys cannot be null");
        }

        long hashCode;
        try {
            hashCode = (long) mapType.getKeyBlockHashCode().invokeExact(keyBlock, position);
        }
        catch (RuntimeException e) {
            throw e;
        }
        catch (Throwable throwable) {
            throw new RuntimeException(throwable);
        }

        return computePosition(hashCode, hashTableSize);
    }