JSON escaping requirements
If a parameter within the JSON formatted parameters template is a JSON structure in itself, it needs to be escaped before adding it as a value - this has two implications:
custom content needs to be escaped, which can be achieved with one of the many offline and online tools for this purpose, for example Code Beautify's Javascript Escape/Unescape
variables with conflicting content (notably multi line variables like JIRA's $issue.descriptionor Bamboo's$notification.textEmailContent)can not currently be used in this context (while all variables are escaped by default, they need to be escaped again when used within an already nested JSON structure) - this will be addressed in an near future release