It was discovered during the analysis of https://github.com/jenkinsci/jenkins/pull/3969/

parent.getJSONObject(name) may throw a JSONException "if the key is not found or if the value is not a JSONObject". http://javadox.com/org.json/json/20151123/org/json/JSONObject.html#getJSONObject-java.lang.String- . In such case Jenkins will still throw a proper Error in the most of configuration form submissions, but it might become an issue for other API usages like Groovy plugin. So it is better to fix it