Problems w/ automatic client inside a cluster...

Reported by a user:

Hey everyone! I am having an issue running the new java-client inside a cluster. I am using
```java
ApiClient client = Config.defaultClient();
Configuration.setDefaultApiClient(client);
```
to acquire a client, which works locally, but I get this when the code is executed inside a cluster:
```java
java.lang.RuntimeException: No OAuth2 authentication configured!
```

