presto-hive/src/main/java/io/prestosql/plugin/hive/HiveBooleanParser.java/HiveBooleanParser/toUpperCase
class HiveBooleanParser:    @SuppressWarnings("NumericCastThatLosesPrecision")
    private static byte toUpperCase(byte b)
    {
        return isLowerCase(b) ? ((byte) (b - 32)) : b;
    }