presto-spi/src/main/java/io/prestosql/spi/block/ShortArrayBlockBuilder.java/ShortArrayBlockBuilder/build
class ShortArrayBlockBuilder:    @Override
    public Block build()
    {
        if (!hasNonNullValue) {
            return new RunLengthEncodedBlock(NULL_VALUE_BLOCK, positionCount);
        }
        return new ShortArrayBlock(0, positionCount, valueIsNull, values);
    }