presto-main/src/main/java/io/prestosql/operator/scalar/StringFunctions.java/StringFunctions/upper
class StringFunctions:    @Description("converts the string to upper case")
    @ScalarFunction
    @LiteralParameters("x")
    @SqlType("varchar(x)")
    public static Slice upper(@SqlType("varchar(x)") Slice slice)
    {
        return toUpperCase(slice);
    }