The BDKs serve to ease building of Symphony bots and do not actually deliver any webhook functionality, so it would be incorrect to say it exists in the Java version. What does exist is a Spring Boot integration for the Java BDK, which uses Spring Boot Core. This can be changed to Spring Boot Web that contains an embedded web server that can be used to listen on a webhook. Symphony does not maintain nor provide support for that so you will have to refer to Spring's documentation.

Likewise, you would need a similar embedded web server for Python if you wish to colocate a webhook listener with your Python BDK bot. Again, Symphony does not maintain nor provide support for that so you will have to check with the respective vendor.