Quite often, we need to build automation around Java desktop apps. The default MS UI automation framework would not be able to identify Java UI components (based on Swing).
Hence we need to use a bridge..and this technology is called as JAB (Java Access Bridge). Using the JAB dll on windows, you can access Java client UI controls and build your automation use-case. All commercial tools such as UiPath, AA also use JAB behind the scenes for Java desktop automation.
Google has also released a cool tool called "Access Bridge Explorer" that can allows exploring, as well as interacting with, the Accessibility tree of any Java applications that uses the Java Access Bridge to expose their accessibility features,