Invalidate the SSH key cache when a user's keys change

Signed-off-by: Shawn O. Pearce <sop@google.com>

appjar/src/main/java/com/google/gerrit/server/AccountSecurityImpl.java

@@ -76,6 +76,7 @@ public class AccountSecurityImpl extends BaseServiceImplementation implements
           newKey.setInvalid();
         }
         db.accountSshKeys().insert(Collections.singleton(newKey));
+        SshUtil.invalidate(db.accounts().get(me));
         return newKey;
       }
     });
@@ -96,6 +97,7 @@ public class AccountSecurityImpl extends BaseServiceImplementation implements
           final Transaction txn = db.beginTransaction();
           db.accountSshKeys().delete(k, txn);
           txn.commit();
+          SshUtil.invalidate(db.accounts().get(me));
         }
 
         return VoidResult.INSTANCE;

appjar/src/main/java/com/google/gerrit/server/ssh/SshUtil.java

@@ -139,8 +139,10 @@ public class SshUtil {
 
   /** Invalidate all cached keys for the given account. */
   public static void invalidate(final Account acct) {
-    synchronized (keys) {
-      keys.remove(acct.getPreferredEmail());
+    if (acct != null) {
+      synchronized (keys) {
+        keys.remove(acct.getPreferredEmail());
+      }
     }
   }