presto-hive/src/main/java/io/prestosql/plugin/hive/coercions/DecimalCoercers.java/DecimalCoercers/createRealToDecimalCoercer
class DecimalCoercers:    public static Function<Block, Block> createRealToDecimalCoercer(DecimalType toType)
    {
        if (toType.isShort()) {
            return new RealToShortDecimalCoercer(toType);
        }
        else {
            return new RealToLongDecimalCoercer(toType);
        }
    }