Fix adding more implied roles in the RoleHierarchy Builder.

[nielsbasjes]

[ As requested by @marcusdacoregio in this comment ]

When defining a RoleHierarchy you can use the text format and the Builder model.

In the text format you can specify

   ROLE_A > ROLE_B
   ROLE_A > ROLE_C

which gives 'A' both 'B' and 'C'

The same specification in the Builder

RoleHierarchyImpl.withDefaultRolePrefix()
    .role("A").implies("B")
    .role("A").implies("C")
    .build();

which gives 'A' only 'C'

Rootcause: doing implies wipes any previous specifications for the same source role.

This fixes that and makes the Builder behave the same as the text format.

[nielsbasjes]

Apologies for putting in merge request with a checkstyle problem.
I tried to check the format locally but that failed.
Now I know this is a problem others have already reported #14575

[marcusdacoregio]

Thanks @nielsbasjes, this is now merged into main.

I am considering this as an enhancement for now, but we can consider backporting it if we receive feedback about users needing it in older versions.