How get Epic Name for Issue? AtlassianSDK | .NET | C#

Used Atlassian.NET SDK. At moment, i do so:

Perform request, like:

var result = jira.Issues.GetIssuesAsync("list_issue_keys");

Iterate result and check custom field Epic Link. If custom field Epic Link is exists, then performs second request:

var result = jira.Issues.GetIssue("epic_link"); and extract it Summary.

If try extract custom field Epic Name directly in result of first request, then thrown exception. Field does not exists.

How wrote right? It possible per one request?