Run jar -tf obf-jar-id-353911.jar-out.jar in your terminal to list all files contained within the archive.
Use tools like JD-GUI or Bytecode Viewer to open the .jar file and view the decompiled Java source code, even if it is obfuscated. obf-jar-id-353911.jar-out.jar
To determine what is inside this file, you can analyze it using the following methods: Run jar -tf obf-jar-id-353911