Docker configuration uses uid for group id (gid) and doesn't have an option for setting gid

Trying to setup Docker I failed to properly configure the user.
Trying to configure a user with user-id and group-id but release pom only has docker.brxm.container.uid. Lookin and in the Dockerfile [1] the uid is used for both gid and uid which to my knowledge is nonsensical:
&& adduser --gid ${docker.brxm.container.uid} --uid ${docker.brxm.container.uid} ${docker.brxm.container.username} \

[1] https://code.onehippo.org/cms-community-dev/hippo-project-archetype/blob/release/13.2/main/src/main/resources/archetype-resources/src/main/docker/Dockerfile