I noticed that the "Edit Issue" REST API docs contain an example request which has some invalid JSON. If you take a look at the "properties" section, it is as follows (I've expanded it, so the error can be more easily seen):
"properties":[
{"key":"key1","value":'properties' : 'can be set at issue create or update time'},
{"key":"key2","value":'and' : 'there can be multiple properties'}
]
The "value" for each property contains two single-quoted strings separated by a semi-colon. I believe it's meant to be something like:
"properties":[
{"key":"key1","value":"properties can be set at issue create or update time"},
{"key":"key2","value":"and there can be multiple properties"}
]
Though I think it's just as clear if you use the values "value1" and "value2" instead.
Sorry if this isn't the right place to submit documentation issues - I couldn't see any links on the page itself.