The name of the JQL function is linkedIssuesInJQL.
It takes from one to three parameters:
|1||string||JQL query||Query returning all linked issues||yes|
|2||string||Issue Link type||Name of the linking. All Issue Link types can be found in JIRA Administration page described in: https://confluence.atlassian.com/adminjiraserver073/configuring-issue-linking-861253998.html||optional|
|3||string||Direction||Direction of the linking. Can be "inward" or "outward".||optional|
Examples of usage: