Hi,

While I was trying JIRA's REST API Browser in Administration section of JIRA, I wanted to test adding 1 new comment to an existing issue, through the REST API.

I've selected "Atlassian JIRA - Plugins - REST Plugin" on the top left select box and then clicked (had to click twice) on "/issue/{issueIdOrKey}/comment". Then, I tested to see first if the GET method will work and it did. After that, I tried to see if the POST method will work, providing the same issue id as in the GET method, not changing the default post data in the box ("body": "Lorem ipsum ..."). After I clicked the "Execute" button, I've got an html page as a response, basicaly saying:

<p>
<b>Cause: </b><br/>
javax.ws.rs.WebApplicationException: java.lang.IllegalArgumentException: Error parsing media type ', application/xml'
</p>

I've opened up the "Developer Tools" (using Google Chrome) and switched to the "Network" tab, to see the request and this is what the request looked like (pay attention to "Content-Type" header field):

Request URL:http://localhost:2990/jira/rest/api/2/issue/TP-1/comment
Request Method:POST
Status Code:500 Internal Server Error
Request Headers view parsed
POST /jira/rest/api/2/issue/TP-1/comment HTTP/1.1
Host: localhost:2990
Connection: keep-alive
Content-Length: 285
Accept: application/json, text/javascript, /; q=0.01
Origin: http://localhost:2990
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/27.0.1453.116 Safari/537.36
Content-Type: , application/xml
Referer: http://localhost:2990/jira/plugins/servlet/restbrowser
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8

{
"body": "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque eget venenatis elit. Duis eu justo eget augue iaculis fermentum. Sed semper quam laoreet nisi egestas at posuere augue semper.",
"visibility":

{ "type": "role", "value": "Administrators" }

}

My version of JIRA is: v5.1.8#787-sha1:823790c but I'll test tomorrow if this issue is present in the latest jira 6.x too.