Snippet: Adding Legends to PlantUML Diagrams

@startuml
skinparam legendBackgroundColor transparent
skinparam legendBorderColor transparent

actor Editor as editor
queue Queue as "Message\nQueue"
editor -> [Component] : call
[Component] --> Queue : publish


legend right
{{
   scale 0.7
   skinparam defaultFontSize 14
   skinparam BackGroundColor transparent
   skinparam defaultBackgroundColor white

   !procedure $entry($type, $label, $scale=1)
      {{\nscale $scale \nskinparam backgroundcolor transparent\nlabel " " as A\nlabel " " as B\n $type \n}} => $label
   !endprocedure

   map "<b>Legend</b>" as legend #white {
      $entry(":Editor:","\nEditor for Data xyz", 0.6)
      $entry("[Component]","\nSome Component", 0.8)
      $entry("queue Queue","\nKafka-Topic", 1)
      $entry("A -> B","Data-Flow")
   }
}}

endlegend
@enduml