The documentation on Plugin Cards

The documentation on Plugin Cards is really lacking important information.
I only found this documentation and it only contains a go template. If I want to use bash for example I am completely lost. I took a look at the go examples and figured out that the json data part needs to be encoded as ansi integer. However there is no information about the control characters that are printed by the go code.
How does drone expect the control charakters "\u001B]1338;" and "\u001B]0m"? As literal characters or as control codes?
How important is it that the encoded json contains no spaces and new lines?