I can see Magento API requires OAuth 1.0 parameters, as opposed to OAuth 2.0.
We can do complex and simple OAuth2 .0 flows (except for the cases where SAML or JWT tokens are required) in the studio but I'm not aware of any explicit support being available for OAuth 1.0.
We have OAuth 1.0 client utilities in CXF so one option is to use either tREST or tRESTClient with tJava sitting in from of tREST and preparing an OAuth 1.0 signature - this is easy enough to do with the utilities, and then tREST would simply pass along HTTP Authorization headers with all OAuth 1.0 parameters listed. Let me know please if you'd like to experiment, see:
Alternatively you can probably indeed use Magento API client library