presto-spi/src/main/java/io/prestosql/spi/block/ArrayBlockEncoding.java/ArrayBlockEncoding/readBlock
class ArrayBlockEncoding:    @Override
    public Block readBlock(BlockEncodingSerde blockEncodingSerde, SliceInput sliceInput)
    {
        Block values = blockEncodingSerde.readBlock(sliceInput);

        int positionCount = sliceInput.readInt();
        int[] offsets = new int[positionCount + 1];
        sliceInput.readBytes(Slices.wrappedIntArray(offsets));
        boolean[] valueIsNull = decodeNullBits(sliceInput, positionCount).orElseGet(() -> new boolean[positionCount]);
        return createArrayBlockInternal(0, positionCount, valueIsNull, offsets, values);
    }