Fix OAuthProtocol equality predicate

The way OAuthProtocol was checked for equality was not performing well
and triggering stack-overflows because of the recursive equality check.

Change-Id: I6140b544fbffcd156dca379ebfdf0b82f0334004

github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java

diff --git a/github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java b/github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java
index 088b70e..f1ef494 100644
--- a/github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java
+++ b/github-oauth/src/main/java/com/googlesource/gerrit/plugins/github/oauth/OAuthProtocol.java
@@ -238,7 +238,16 @@
 
     @Override
     public boolean equals(Object obj) {
-      return Objects.deepEquals(this, obj);
+      if (obj == null) {
+        return false;
+      }
+      if (getClass() != obj.getClass()) {
+        return false;
+      }
+      final AccessToken other = (AccessToken) obj;
+      return Objects.equals(this.accessToken, other.accessToken)
+          && Objects.equals(this.raw, other.raw)
+          && Objects.equals(this.tokenType, other.tokenType);
     }
 
     public boolean isError() {