如何在PlantUML的图例中定义要精灵化的背景颜色？

问题描述

底部的代码生成下面的输出。如何将子画面的背景色（白色）设置为背景色（紫色）？

@startuml Archimate

skinparam defaultTextAlignment center
skinparam backgroundColor #EEEBDC

skinparam Legend {
    BackgroundColor #EEEBDC
    FontColor #000000
    BorderThickness 0
}

!define ICONURL https://raw.githubusercontent.com/tupadr3/plantuml-icon-font-sprites/v2.2.0
!include ICONURL/common.puml
!include ICONURL/devicons2/docker.puml

skinparam componentStyle rectangle
skinparam ArrowColor #546E7A

!define _dockerbackgroundcolor #7B1FA2
!define _dockercolor #CE93D8
!define _dockercoloralternate #F48FB1
!define _dockertextcolor #FFFFFF

DEV2_DOCKER(app1,<color:_dockertextcolor>FileMonitor,component,_dockercolor) _dockerbackgroundcolor
DEV2_DOCKER(app2,<color:_dockertextcolor>DataAPI,_dockercoloralternate) _dockerbackgroundcolor

app1 -down-> app2

legend right
|<_dockerbackgroundcolor><color:_dockercolor><$docker>    | App1 |
|<_dockerbackgroundcolor><color:_dockercoloralternate><$docker> | App2 |
endlegend

@enduml

解决方法

根据here，这是一个错误。