Can you please give an example of credental_file, for a self-hosted buildbarn remote instance to work?

[raphael10-collab]

As described here: bazelbuild/reclient#10

in Rewrapper flags there is no flag for authentication settings : https://github.com/bazelbuild/reclient/blob/main/docs/cmd-line-flags.md#rewrapper but I get this error : Unable to authenticate with RBE service needs to be specified, authentication type (identity) used="unknown authentication type

Since according to https://github.com/bazelbuild/reclient/blob/main/docs/cmd-line-flags.md#notes-on-credentials-and-authentication-source one of these flags :

1. credential_file,
2. use_application_default_credentials,
3. use_gce_credentials

is mandatory,

can you please give an example of credental_file, for a self-hosted buildbarn remote instance to work?