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hqlLinkedIssues
hqlLinkedIssuesOf
The JQL function search for issues linked to at least one issue satisfying the condition specified on the filter and, if specified, having the specified link type and link direction.
Examples
To find all the issues that are blocked by issues in a state not equal to Done, you could use:
issue in hqlLinkedIssuesOf("status!=done", "Blocks", "O")