Method validate must be return a Bpmn2ChoreographyValidatorResponse
Change the return type of the validate(...) method of the class Bpmn2ChoreographyValidator to Bpmn2ChoreographyValidatorResponse
also remove "throws Bpmn2ChoreographyValidatorException" in the methods addErrors(...) and addError(...) of the class Bpmn2ChoreographyValidatorResponse