Allow changing nested fields limit for open indices

Author: Yannick Welsch

core/src/main/java/org/elasticsearch/cluster/ClusterModule.java

@@ -67,6 +67,7 @@
 import org.elasticsearch.gateway.PrimaryShardAllocator;
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.IndexingSlowLog;
+import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.search.stats.SearchSlowLog;
 import org.elasticsearch.index.settings.IndexDynamicSettings;
 import org.elasticsearch.index.MergePolicyConfig;
@@ -181,6 +182,7 @@ private void registerBuiltinIndexSettings() {
         registerIndexDynamicSetting(IndicesRequestCache.INDEX_CACHE_REQUEST_ENABLED, Validator.BOOLEAN);
         registerIndexDynamicSetting(UnassignedInfo.INDEX_DELAYED_NODE_LEFT_TIMEOUT_SETTING, Validator.TIME);
         registerIndexDynamicSetting(DefaultSearchContext.MAX_RESULT_WINDOW, Validator.POSITIVE_INTEGER);
+        registerIndexDynamicSetting(MapperService.INDEX_MAPPING_NESTED_FIELDS_LIMIT_SETTING, Validator.NON_NEGATIVE_INTEGER);
     }
 
     public void registerIndexDynamicSetting(String setting, Validator validator) {