GHRepository owner is NOT a GHUser but more generically a GHPerson.

When GitHub repositories are associated to organisations,
the owner is NOT the user but the org itself.

src/main/java/org/kohsuke/github/GHPerson.java

@@ -14,7 +14,7 @@
  * 
  * @author Kohsuke Kawaguchi
  */
-public abstract class GHPerson {
+public class GHPerson {
     /*package almost final*/ GitHub root;
 
     // core data fields that exist even for "small" user data (such as the user info in pull request)

src/main/java/org/kohsuke/github/GHRepository.java

@@ -57,7 +57,7 @@ public class GHRepository {
     private String description, homepage, name;
     private String url; // this is the API url
     private String html_url;    // this is the UI
-    private GHUser owner;   // not fully populated. beware.
+    private GHPerson owner;   // not fully populated. beware.
     private boolean has_issues, has_wiki, fork, _private, has_downloads;
     private int watchers,forks,open_issues,size;
     private String created_at, pushed_at;