There were/are Java EE frameworks, that enable to have a class with normal control flow like a Java SE application, and thus maintain state. To function over HTTP at specific points the classes instance is serialized, a response is made to the client, and on the next request the instance is deserialized and continues. This is not a general purpose coroutine solution, and I would certainly not call fibers.
Unfortunately its name slips my mind. But that was a specific case of running one single coroutine transfering control to the framework coroutine.
AOP offers another mean to switch control. Could maybe be used to implement fibers.