How to define FieldScreen used in current issue/transition page?

[Asiya Khakimova]

I need to be able to determine which FieldScreen used in current issue page.

I found that i can achieve that for create/view/edit page via sending JIRA.Issue.getIssueId() to backend:

Issue issue = ComponentAccessor.getIssueManager().getIssueObject(issueId);

FieldScreenScheme fieldScreenScheme = ComponentAccessor.getIssueTypeScreenSchemeManager().getFieldScreenScheme(issue);

FieldScreen fieldScreen = fieldScreenScheme.getFieldScreen(?????);

But how to define IssueOperation?

And what about Workflow transition screens - how to define them?