Google's common expression language supports bytes literal, which I think is a good function. I hope spring expression can also expand this capability
b"\\x61\\x62\\x63" will be resolved to abc
b"abc\\x61\\x62\\x63" will be resolved to abcabc
prefix:b' or b"
suffix: ' or "
Reference: https://github.com/google/cel-spec/blob/master/doc/langdef.md