By default elements in a PlantUML generated diagram have shadows. To disable shadows we must set the skin parameter shadowing to the value false. PlantUML will then not create shadows on elements.

In the following sample PlantUML definition we use the value false for the skin parameter shadowing:


' Remove shadows
skinparam shadowing false

actor User
[Third party application] as ThirdPartyApp

package "Spring Boot Application" {
    rectangle Controllers <<Spring REST controllers>>
    rectangle DataStoreService <<Spring service>>
    rectangle Repository <<Spring repository>>

User --> Controllers
ThirdPartyApp --> Controllers

Controllers --> DataStoreService
DataStoreService --> Repository


The generated diagram has no shadows:

Written with PlantUML 8086.

Original blog post