presto-spi/src/main/java/io/prestosql/spi/block/AbstractArrayBlock.java/AbstractArrayBlock/isNull
class AbstractArrayBlock:    @Override
    public boolean isNull(int position)
    {
        checkReadablePosition(position);
        boolean[] valueIsNull = getValueIsNull();
        return valueIsNull == null ? false : valueIsNull[position + getOffsetBase()];
    }