The following code fails (though it shouln't):
@startuml
component a {
}
note top of a: \n==theme fail==\n{{\n!theme crt-amber\nUser->System: test\n}}\n
@enduml
Please have a look:
http://www.plantuml.com/plantuml/umla/9SWn2W8n40NGFgSO3x0NM8YN4Bjful8N1VCd9B-HaBjRx2lV4RK5GLcncLPA3C4KpUAqifipPxrHOMVvV7DspkcyNNLqRQM-q9tFWRxT7xyXrDs48UTQplG7