MXMLFileScope fileScope = builder.getFileScope();
ClassDefinition definitionTagClass =
fileScope.getClassDefinitionForDefinitionTag(tag);
assert tagDefinition == definitionTagClass.resolveBaseClass(project);
containedClassDefinitionNode.setClassReference(project, tagDefinition); // TODO Move this logic to initializeFromTag().
containedClassDefinitionNode.setClassDefinition(definitionTagClass); // TODO Move this logic to initializeFromTag().
containedClassDefinitionNode.initializeFromTag(builder, childTag);