We are new to Jira Server. We hosted it on our own server. We have some rest api's which we need to call and get the values and put the values in custom field select multiselect options. We searched that there is scriptrunner plugin. We should not use that. We found that, for Jira cloud, there is an app called 'External data for Jira Fields', but this app designed and works only for jira cloud, not for jira core server . The same functionality we need to achieve for jira core server. What are the possible ways to do it?