Add explicit cast to fix compile error on Java 8

Change-Id: I8a35158ee2d70ec2c878621ca35c686ab9fc19f6
diff --git a/gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshDaemon.java b/gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshDaemon.java
index 94967f0..3306592 100644
--- a/gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshDaemon.java
+++ b/gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshDaemon.java
@@ -411,8 +411,8 @@
 
     a.add(null);
     a.add(new CipherNone.Factory());
-    setCipherFactories(filter(cfg, "cipher", a.toArray(new NamedFactory[a
-        .size()])));
+    setCipherFactories(filter(cfg, "cipher",
+        (NamedFactory<Cipher>[])a.toArray(new NamedFactory[a.size()])));
   }
 
   private void initMacs(final Config cfg) {