Don't index missing accounts

AccountCache#get returns an empty AccountState instance for missing
accounts. Rather use AccountCache#getOrNull and don't index missing
accounts.

Change-Id: I6984e3c9cfc452fb8991031e1a5283a6792b4d96
Signed-off-by: Edwin Kempin <ekempin@google.com>

gerrit-server/src/main/java/com/google/gerrit/server/index/account/AccountIndexerImpl.java

diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/index/account/AccountIndexerImpl.java b/gerrit-server/src/main/java/com/google/gerrit/server/index/account/AccountIndexerImpl.java
index 58dbd34..8796360 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/index/account/AccountIndexerImpl.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/index/account/AccountIndexerImpl.java
@@ -64,8 +64,13 @@
 
   @Override
   public void index(Account.Id id) throws IOException {
-    for (Index<?, AccountState> i : getWriteIndexes()) {
-      i.replace(byIdCache.get(id));
+    for (Index<Account.Id, AccountState> i : getWriteIndexes()) {
+      AccountState accountState = byIdCache.getOrNull(id);
+      if (accountState != null) {
+        i.replace(accountState);
+      } else {
+        i.delete(id);
+      }
     }
     fireAccountIndexedEvent(id.get());
   }