Recovery from ChangeSet compilation fail

Drools org.drools.compiler.PackageBuilder has a bug in loading change-sets containing damaged resources. Compilation of such change-set prevents builder recovery even by using undo() method.

When user adds new Drools resource into KnowledgeBuilder, its implementation KnowledgeBuilderImpl on line 50 calls PackageBuilder to register the change set file as an official resource.

In a following step the PackageBuilder extracts all mentioned resources from that change-set file and processes each of them separately but without their official registration in loaded resources. But these resources are processed under their own resource name which is the key in the set of reported errors.

Due to such behavior there remains errors preventing building stable org.drools.KnowledgeBase with an IllegalArgumentException even after calling KnowledgeBuilder#undo(), because it removes only errors reported directly with the change-set resource, but not the errors reported with resources from the change-set.