loadMessages return list of DocumentMessage.

[rsp-nsi]

I have some troubles with EhboxService and the function loadMessages.
I don’t understand why this method returns a List of Messages and not a List of DocumentMessage ?
During some tests on eHealthBox my eHealthMessage have DocumentMessage properties.

override fun loadMessages(
        keystoreId: UUID,
        tokenId: UUID,
        passPhrase: String,
        boxId: String,
        limit: Int?,
        alternateKeystores: List<AltKeystore>?
    ): List<Message>