Can't set issue assignee using Jira API Rest Client 5.2 using issueBuilder.

[Diego Daibert]

I'm trying to create an issue using IssueBuilder and I can't add an assignee to this issue. 
I have already used the methods setAssigne(BasicUser user) and setAssigneeName(String name). The name doesn't longer exist in the object returned by JIRA. And when I set the BasicUser the error shows that is impossible to set an assignee with an user that doesn't have a name.