You might want to exclude a certain file from obfuscation. This might be the case if the class is used in an extension of your plugin.
To exclude a class from obfuscation you have to add a statement like
-keep class de.example.plugin.actions.MySpecialAction {
public protected *;
}to the proguard.cfg file. All other classes in the package de.example.plugin.actions are completely obfuscated.
Remark: If you modified the proguard.cfg file manually, then these changes will be lost when re-generating the configuration!