Error When Testing a JQL Query

The following error occurs when you test a Jira Query Language (JQL) query on the Operations page of the Adapter Endpoint Configuration Wizard and there is any null value present in the JQL result.

(issuelinks) Array element is empty. Please add more than one element in this 
array and then do the json sampling. Check the error stack and fix the cause of the error. 
Contact oracle support if error is not fixable.

Solution: Replace all the null values (that is, [] ) with double quotation marks ("") in the JQL result.