title: Redmine plugin for Jenkins: org.json.JSONException: A JSONObject text must begin with '{' at character 1
body: <p>I am rethrieving the next error in Jenkins when trying to get Redmine Metrics:</p>
  
  <pre><code>hudson.plugins.redmine.MetricsException: com.taskadapter.redmineapi.RedmineFormatException: org.json.JSONException: A JSONObject text must begin with '{' at character 1
  Build step 'Aggregate Redmine ticket metrics' marked build as failure
  Notifying upstream projects of job completion
  Finished: FAILURE
  </code></pre>
  
  <p>Any idea of what could cause the error?</p>