Incompatible class files

I am working on an app where it retrieves all user data from the server in an object called, appropriately, User.
However, since this class is in a package, it needs to be in the same package on the client side.

The problem is that this is very impractical since the User classes are in different packages and I don’t want to create special packages just to accommodate this 1 class.

Is there any remedy to this problem?

Abstract the data transfer from the model objects representing the user. The lowest level example of this would be to send the user information manually as strings or byte buffers (or serialized JSON) and then parsing the data back into the client’s user object. In this case there would be no need for the client and server to share any code. Alternatively, if you’re using RMI and need to share class definitions, define a POJO bean to act as the transfer object and share those across the client and server, but your user classes that actually have logic can be separate.

I had hoped to avoid just sending strings.
I want the easiest way possible using plain ObjectOutputStream and ObjectInputStream (I don’t like KryoNet).
Sending the entire data in the User class as a String then parsing it back is going to be a hassle.

Also I don’t need to use RMI here but what is a POJO bean?