I am searching a working oauth2 provider server implemented on java, leeloo and spring security are some that I have found, but there is no working example.
https://github.com/SpringSource/spring-security-oauth/wiki/tutorial
https://bitbucket.org/smartproject/oauth-2.0/wiki/Home
There is the Apache Oltu (formerly Apache Amber) implementation that supports building OAuth 2.0 Authorization and Resource Servers: https://cwiki.apache.org/confluence/display/OLTU/OAuth+2.0+Authorization+Server and is not dependent on any framework.
You have examples of AS (Auth and Token endpoints) and RS test implementation in integration tests: https://github.com/apache/oltu/tree/trunk/oauth-2.0/integration-tests/src/test/java/org/apache/oltu/oauth2/integration/endpoints
ınside spring security package there has 2 example one tonr other sparklr implemented with oauth2
Bit late, but you could - for future references - have a look at https://github.com/OpenConextApps/apis.
