0001-Fix-fix-SnakeYaml.patch.gz
OK, I had a look and this is my finding: I took some of your changes from a8b7aac and I changed the model. It looks like you cannot make snakeyaml-writer and snakeyaml-extended-reader from the same model. Because the extended reader requires locationTracker parameter in the root element. But with this parameter, the AbstractJavaModelloGenerator::isTrackingSupport is true and the class Model will be not relevant (isRelevant == false) and it will not be returned by getClasses(objectModel) in SnakeYamlWriterGenerator.
With the changes it produces compilable code.

Also I changed the org.apache.maven.model package to org.codehaus.modello.test.model, because maven has itself the org.apache.maven.model.Model class in the org.apache.maven:maven-model artifact and it is safer to not have two unrelated classes on the classpath with the same full qualified name.

Applied and yay! Thanks @fridrich a lot!

I hope it is fix for: #367 and suppresses #419