[proguard-maven-plugin] Improvement: Optional & provided dependencies should be added to "-libraryjars"

[Dmitry Katsubo]

The problem occurs with dependencies like commons-logging, which have runtime dependencies to other logging engines. As workaround one can use

<assembly>
    <inclusions>
         <inclusion>
             <groupId>log4j</groupId>
             <artifactId>log4j</artifactId>
         </inclusion>

...

</assembly>

but all these dependencies are already listed as optional / provided in the dependency tree. Thus they should be added as "-libraryjars" to avoid warnings.

List of warnings:

 [proguard] Warning: org.apache.commons.logging.impl.AvalonLogger: can't find referenced class org.apache.avalon.framework.logger.Logger
 [proguard] Warning: org.apache.commons.logging.impl.Log4JLogger: can't find referenced class org.apache.log4j.Category
 [proguard] Warning: org.apache.commons.logging.impl.Log4JLogger: can't find referenced class org.apache.log4j.Priority
 [proguard] Warning: org.apache.commons.logging.impl.Log4JLogger: can't find referenced class org.apache.log4j.Logger
 [proguard] Warning: org.apache.commons.logging.impl.LogKitLogger: can't find referenced class org.apache.log.Hierarchy
 [proguard] Warning: org.apache.commons.logging.impl.LogKitLogger: can't find referenced class org.apache.log.Logger
 [proguard] Warning: org.apache.commons.logging.impl.ServletContextCleaner: can't find referenced class javax.servlet.ServletContextListener
 [proguard] Warning: org.apache.commons.logging.impl.ServletContextCleaner: can't find referenced class javax.servlet.ServletContextEvent