Make abstract

Author: alexey-ivanov-es

server/src/main/java/org/elasticsearch/common/settings/BaseSettingsUpdater.java

@@ -17,7 +17,7 @@
 
 import static org.elasticsearch.common.settings.AbstractScopedSettings.ARCHIVED_SETTINGS_PREFIX;
 
-public class BaseSettingsUpdater {
+public abstract class BaseSettingsUpdater {
     protected final AbstractScopedSettings scopedSettings;
 
     public BaseSettingsUpdater(AbstractScopedSettings scopedSettings) {