Adapt to change in Gerrit core

The supportsHtml method was removed by change Iaa95de203.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: Iedbf036cb13c731d4742ce81c22ff45cef8cd6cb
diff --git a/java/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedSender.java b/java/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedSender.java
index 26e4841..986e0eb 100644
--- a/java/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedSender.java
+++ b/java/com/google/gerrit/plugins/checks/email/CombinedCheckStateUpdatedSender.java
@@ -164,9 +164,4 @@
       appendHtml(soyHtmlTemplate("CombinedCheckStateUpdatedHtml"));
     }
   }
-
-  @Override
-  protected boolean supportsHtml() {
-    return true;
-  }
 }