declare StateEvent
	@role( event )
	@timestamp( startTime )
	@duration( duration )
end

import java.sql.Timestamp;
...
    private Timestamp startTime;
    private Long duration;
    public Timestamp getStartTime() {
        return startTime;
    }
    public void setStartTime(Timestamp st) {
        startTime = st;
    }
    public Long getDuration() {
        return duration;
    }
    public void setDuration(Long d) {
        duration = d;
    }
....

KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
kbuilder.add(ResourceFactory.newClassPathResource("path-to-file", ResourceType.DRL);

Annotated type StateEvent - undefined property in @annotation timestamp: java.sql.Timestamp.value();