I startet to experiment with the drools-solver but only got a NullPointerException:

Caused by: java.lang.NullPointerException
at org.drools.common.AbstractRuleBase.addPackages(AbstractRuleBase.java:429)
at org.drools.reteoo.ReteooRuleBase.addPackage(ReteooRuleBase.java:395)
at org.drools.solver.config.localsearch.LocalSearchSolverConfig.buildRuleBase(LocalSearchSolverConfig.java:166)
at org.drools.solver.config.localsearch.LocalSearchSolverConfig.buildSolver(LocalSearchSolverConfig.java:137)
at org.drools.solver.config.XmlSolverConfigurer.buildSolver(XmlSolverConfigurer.java:73)
...

After debugging into this location, I found out that it comes from an error in my scoreDrl.

The buildSolver-Method should fail with a more helpful exception or the result of the PackageBuilder should be available to analyse the problems.