Hello PlantUML team,
From V1.2020.17, this is correct for text, but not if we use Creole horizontal separator line:
See old remarks:
And here are some new examples:
1/ From the example of /10967:
@startuml
rectangle r as "
Text as top
==
{{
salt
{{T
+ <&folder>Folder1
}
}
}}
"
note left of r
Text as top
==
{{
salt
{{T
+ <&folder>Folder1
}
}
}}
end note
@enduml

[See on PlantUML server]
2/ OK with text
@startuml
rectangle r [
{{
file f1
}}
text between f1 and f2
{{
file f2
}}
{{
file f3
}}
]
@enduml

3/ KO with line:
@startuml
rectangle r [
{{
file f1
}}
-- text between f1 and f2 --
{{
file f2
}}
{{
file f3
}}
]
@enduml

[See...]
Thanks for your support,
Regards,
Th.