Move query interceptor to an internal plugin interface (#120308)

Query interceptor is meant for internal modules to implement, not any
external plugin. Yet it is defined on SearchPlugin that is available to
all plugin authors. This commit creates an InternalSearchPlugin
interface and moves the query interceptor method to that.

Author: rjernst

server/src/main/java/module-info.java

@@ -394,6 +394,7 @@
     exports org.elasticsearch.action.downsample;
     exports org.elasticsearch.plugins.internal
         to
+            org.elasticsearch.inference,
             org.elasticsearch.metering,
             org.elasticsearch.stateless,
             org.elasticsearch.settings.secure,

server/src/main/java/org/elasticsearch/indices/IndicesServiceBuilder.java

@@ -34,7 +34,7 @@
 import org.elasticsearch.plugins.EnginePlugin;
 import org.elasticsearch.plugins.IndexStorePlugin;
 import org.elasticsearch.plugins.PluginsService;
-import org.elasticsearch.plugins.SearchPlugin;
+import org.elasticsearch.plugins.internal.InternalSearchPlugin;
 import org.elasticsearch.plugins.internal.rewriter.QueryRewriteInterceptor;
 import org.elasticsearch.script.ScriptService;
 import org.elasticsearch.search.aggregations.support.ValuesSourceRegistry;
@@ -266,8 +266,8 @@ public IndicesService build() {
             .flatMap(m -> m.entrySet().stream())
             .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
 
-        var queryRewriteInterceptors = pluginsService.filterPlugins(SearchPlugin.class)
-            .map(SearchPlugin::getQueryRewriteInterceptors)
+        var queryRewriteInterceptors = pluginsService.filterPlugins(InternalSearchPlugin.class)
+            .map(InternalSearchPlugin::getQueryRewriteInterceptors)
             .flatMap(List::stream)
             .collect(Collectors.toMap(QueryRewriteInterceptor::getQueryName, interceptor -> {
                 if (interceptor.getQueryName() == null) {

server/src/main/java/org/elasticsearch/plugins/SearchPlugin.java

@@ -23,7 +23,6 @@
 import org.elasticsearch.index.query.QueryParser;
 import org.elasticsearch.index.query.functionscore.ScoreFunctionBuilder;
 import org.elasticsearch.index.query.functionscore.ScoreFunctionParser;
-import org.elasticsearch.plugins.internal.rewriter.QueryRewriteInterceptor;
 import org.elasticsearch.search.SearchExtBuilder;
 import org.elasticsearch.search.aggregations.Aggregation;
 import org.elasticsearch.search.aggregations.AggregationBuilder;
@@ -129,14 +128,6 @@ default List<QuerySpec<?>> getQueries() {
         return emptyList();
     }
 
-    /**
-     * @return Applicable {@link QueryRewriteInterceptor}s configured for this plugin.
-     * Note: This is internal to Elasticsearch's API and not extensible by external plugins.
-     */
-    default List<QueryRewriteInterceptor> getQueryRewriteInterceptors() {
-        return emptyList();
-    }
-
     /**
      * The new {@link Aggregation}s added by this plugin.
      */

server/src/main/java/org/elasticsearch/plugins/internal/InternalSearchPlugin.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.plugins.internal;
+
+import org.elasticsearch.plugins.internal.rewriter.QueryRewriteInterceptor;
+
+import java.util.List;
+
+import static java.util.Collections.emptyList;
+
+public interface InternalSearchPlugin {
+
+    /**
+     * @return Applicable {@link QueryRewriteInterceptor}s configured for this plugin.
+     * Note: This is internal to Elasticsearch's API and not extensible by external plugins.
+     */
+    default List<QueryRewriteInterceptor> getQueryRewriteInterceptors() {
+        return emptyList();
+    }
+}

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferencePlugin.java

@@ -39,6 +39,7 @@
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.plugins.SearchPlugin;
 import org.elasticsearch.plugins.SystemIndexPlugin;
+import org.elasticsearch.plugins.internal.InternalSearchPlugin;
 import org.elasticsearch.plugins.internal.rewriter.QueryRewriteInterceptor;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestHandler;
@@ -136,7 +137,14 @@
 import static org.elasticsearch.xpack.inference.services.elastic.ElasticInferenceServiceFeature.DEPRECATED_ELASTIC_INFERENCE_SERVICE_FEATURE_FLAG;
 import static org.elasticsearch.xpack.inference.services.elastic.ElasticInferenceServiceFeature.ELASTIC_INFERENCE_SERVICE_FEATURE_FLAG;
 
-public class InferencePlugin extends Plugin implements ActionPlugin, ExtensiblePlugin, SystemIndexPlugin, MapperPlugin, SearchPlugin {
+public class InferencePlugin extends Plugin
+    implements
+        ActionPlugin,
+        ExtensiblePlugin,
+        SystemIndexPlugin,
+        MapperPlugin,
+        SearchPlugin,
+        InternalSearchPlugin {
 
     /**
      * When this setting is true the verification check that