Populating AEM Component Dialog fields using JSON data returned by Sling Servlets

You can invoke an Adobe Experience Manager (AEM) Sling Servlet to populate fields that appear in AEM component dialog. That is, instead of hard-coding values in JavaScript, you can populate a dialog drop-down using a Servlet’s return value (for example, JSON data),

adobe community: https://helpx.adobe.com/experience-manager/using/custom_columns.html