Allow to update base/override remote configs from MergedConfigResource

Expose the ability to update base or override remote configs
with a single method at MergedConfigResource, as a follow-up of the
introduction of the API to update replication configs from other
plugins.

Change-Id: If9cb404c88e4397bd1c292c2dd1339d14fcc77af

src/main/java/com/googlesource/gerrit/plugins/replication/MergedConfigResource.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/replication/MergedConfigResource.java b/src/main/java/com/googlesource/gerrit/plugins/replication/MergedConfigResource.java
index 43d90a5..315c4a6 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/replication/MergedConfigResource.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/replication/MergedConfigResource.java
@@ -26,6 +26,7 @@
 import com.google.inject.util.Providers;
 import com.googlesource.gerrit.plugins.replication.api.ConfigResource;
 import com.googlesource.gerrit.plugins.replication.api.ReplicationConfigOverrides;
+import java.io.IOException;
 import java.util.function.Supplier;
 import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.Config;
@@ -80,4 +81,12 @@
   private boolean noOverrides() {
     return overrides == null || overrides.get() == null;
   }
+
+  void update(Config remotesConfig) throws IOException {
+    if (noOverrides()) {
+      base.get().update(remotesConfig);
+    } else {
+      overrides.get().update(remotesConfig);
+    }
+  }
 }