gerrit-gpg: Minor cleanups

Change-Id: I0c9b6f4a960f212d9a4839bf1d0b0ae7fba9c99e
diff --git a/gerrit-gpg/src/main/java/com/google/gerrit/gpg/PublicKeyStore.java b/gerrit-gpg/src/main/java/com/google/gerrit/gpg/PublicKeyStore.java
index a36052e..721b101 100644
--- a/gerrit-gpg/src/main/java/com/google/gerrit/gpg/PublicKeyStore.java
+++ b/gerrit-gpg/src/main/java/com/google/gerrit/gpg/PublicKeyStore.java
@@ -303,7 +303,7 @@
     }
     if (toWrite.size() == existing.size()) {
       return;
-    } else if (toWrite.size() > 0) {
+    } else if (!toWrite.isEmpty()) {
       notes.set(keyObjectId(keyId),
           ins.insert(OBJ_BLOB, keysToArmored(toWrite)));
     } else {
diff --git a/gerrit-gpg/src/main/java/com/google/gerrit/gpg/PushCertificateChecker.java b/gerrit-gpg/src/main/java/com/google/gerrit/gpg/PushCertificateChecker.java
index 86a33ab..9dc3e69 100644
--- a/gerrit-gpg/src/main/java/com/google/gerrit/gpg/PushCertificateChecker.java
+++ b/gerrit-gpg/src/main/java/com/google/gerrit/gpg/PushCertificateChecker.java
@@ -154,8 +154,8 @@
         StringBuilder err = new StringBuilder("Invalid public key ")
             .append(keyToString(k))
             .append(":");
-        for (int i = 0; i < result.getProblems().size(); i++) {
-          err.append('\n').append("  ").append(result.getProblems().get(i));
+        for (String problem : result.getProblems()) {
+          err.append("\n  ").append(problem);
         }
         problems.add(err.toString());
         return;