How to debug compiled JAVA Spring MVC jar?

Question

Java

There is a third-party jar file with a Spring MVC (Spring Boot) project that contains a complete application with all dependencies.
How to debug a project using intellij idea (which can decompile code).
That is, you need to climb into when and go in steps.
When I include the jar via the build configuration (Run/Debug Configuration -> JAR Application), the application is launched via the IDE, but how do I include the decompiled sources and step through them in debugging?

Answer 1

as a solution, try to decompile the project. Fortunately, there are plenty of free decompilers, and then assemble them back.