Install libproguard-java by entering the following commands in the terminal:
sudo apt update sudo apt install libproguard-java
Description:
Java class file shrinker, optimizer, and obfuscator (Library)
ProGuard is a free Java class file shrinker, optimizer, and obfuscator. It can detect and remove unused classes, fields, methods, and attributes. It can then optimize bytecode and remove unused instructions. Finally, it can rename the remaining classes, fields, and methods using short meaningless names. The resulting jars are smaller and harder to reverse-engineer. . This package contains the Proguard Java library
Homepage: http://proguard.sourceforge.net
Version: 6.0.1-2
Section: universe/java