Cant set to maintainsession Apache Axis WSDL

SOAP request are new for me and for a project i need to use SOAP reqeusts to a SOAP service.

At first i created a new Project in IntelliJ and clicked "Additional Libraries and Frameworks" -> "Webservice Client" And choose Apache Axis. After that i let intelliJ generate all the code using its generater and got the SOAP service to work and get all requested data.

Now i have an existing java project and when i go to "Add Framework" and go trough all the steps to generate all the objects, it seems that some functions aren't there. In the new created project i had the function setMaintainSession, which i used to keep me authenticated. But it seems to be missing in the existing project. How am i able to use the setMaintainSession function? Or whats the alternative and why isnt this function available?