Atlassian connector for eclipse - Unable to open task

[Ed]

When I search for an existing JIRA issue I get the following error message in Spring Tool Suit 3.7.2 (Eclipse Mars 4.5.1):

com.sun.jersey.api.client.ClientHandlerException: A message body reader for Java class org.codehaus.jettison.json.JSONObject,
and Java type class org.codehaus.jettison.json.JSONObject, and MIME media type text/html;charset=UTF-8
was not found

I have an existing issue in my list and can open that. I haven't updated Eclipse recently or added any new plugins.

[Ed]

I get the same result when I try to add a query that exists in JIRA. When I click on Update from Repository, I get the same error message.