Make sure that we don't have an empty email address from google auth
diff --git a/src/main/java/com/googlesource/gerrit/plugins/oauth/GoogleOAuthService.java b/src/main/java/com/googlesource/gerrit/plugins/oauth/GoogleOAuthService.java
index 80a207f..e02e3cd 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/oauth/GoogleOAuthService.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/oauth/GoogleOAuthService.java
@@ -143,7 +143,7 @@
           }
         }
       }
-      if (useDomainUsersForSsh) {
+      if (useDomainUsersForSsh && !email.isJsonNull()) {
         login = email.getAsString().split("@")[0];
       }
       return new OAuthUserInfo(id.getAsString() /*externalId*/,