Parameter username in not supported in gdpr strict mode

I’m using jira rest client api 5.2.1, but due to GDPR change I have a problem with search user.

Endpoint looks like this:
GET path/search?searchTerm=mar


{ “statusCode”: “ERROR”,
“message”: “java.util.concurrent.ExecutionException: 400\n{“errorMessages”:[“The query parameter ‘username’ is not supported in GDPR strict mode.”],“errors”:{}

This is method from jira client api to search users, and I use this to fill assignee or reporter data.

Promise<Iterable> findUsers(String username, @Nullable Integer startAt, @Nullable Integer maxResults,
@Nullable Boolean includeActive, @Nullable Boolean includeInactive);

Do somebody know how to search user to fill those fields after gdpr change? Is there any “substitution”? What will be with Jira assignee and reporter fields?

Thanx in advance.