Add typless client side GetIndexRequest calls and response class (#38422)

The HLRC client currently uses `org.elasticsearch.action.admin.indices.get.GetIndexRequest`
and `org.elasticsearch.action.admin.indices.get.GetIndexResponse` in its get index
calls. Both request and response are designed for the typed APIs, including some
return types e.g. for `getMappings()` which in the maps it returns still use a
level including the type name.  In order to change this without breaking
existing users of the HLRC API, this PR introduces two new request and response
objects in the `org.elasticsearch.client.indices` client package. These are used
by the IndicesClient#get and IndicesClient#exists calls now by default and
support the type-less API. The old request and response objects are still kept
for use in similarly named, but deprecated methods.

The newly introduced client side classes are simplified versions of the server
side request/response classes since they don't need to support wire
serialization, and only the response needs fromXContent parsing (but no
xContent-serialization, since this is the responsibility of the server-side
class).  Also changing the return type of `GetIndexResponse#getMapping` to
`Map<String, MappingMetaData> getMappings()`, while it previously was returning
another map keyed by the type-name. Similar getters return simple Maps instead
of the ImmutableOpenMaps that the server side response objects return.

Backport for #37778
Relates to #35190

Author: Christoph Büscher

client/rest-high-level/src/main/java/org/elasticsearch/client/IndicesClient.java

@@ -34,10 +34,6 @@
 import org.elasticsearch.action.admin.indices.flush.SyncedFlushRequest;
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeResponse;
-import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
-import org.elasticsearch.action.admin.indices.get.GetIndexResponse;
-import org.elasticsearch.client.indices.GetFieldMappingsRequest;
-import org.elasticsearch.client.indices.GetFieldMappingsResponse;
 import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
 import org.elasticsearch.action.admin.indices.open.OpenIndexResponse;
 import org.elasticsearch.action.admin.indices.refresh.RefreshRequest;
@@ -59,6 +55,10 @@
 import org.elasticsearch.client.indices.CreateIndexRequest;
 import org.elasticsearch.client.indices.CreateIndexResponse;
 import org.elasticsearch.client.indices.FreezeIndexRequest;
+import org.elasticsearch.client.indices.GetFieldMappingsRequest;
+import org.elasticsearch.client.indices.GetFieldMappingsResponse;
+import org.elasticsearch.client.indices.GetIndexRequest;
+import org.elasticsearch.client.indices.GetIndexResponse;
 import org.elasticsearch.client.indices.GetIndexTemplatesRequest;
 import org.elasticsearch.client.indices.GetMappingsRequest;
 import org.elasticsearch.client.indices.GetMappingsResponse;
@@ -901,6 +901,41 @@ public void getAsync(GetIndexRequest getIndexRequest, RequestOptions options,
             GetIndexResponse::fromXContent, listener, emptySet());
     }
 
+    /**
+     * Retrieve information about one or more indexes
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-get-index.html">
+     * Indices Get Index API on elastic.co</a>
+     * @param getIndexRequest the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @return the response
+     * @throws IOException in case there is a problem sending the request or parsing back the response
+     * @deprecated This method uses an old request object which still refers to types, a deprecated feature. The method
+     * {@link #get(GetIndexRequest, RequestOptions)} should be used instead, which accepts a new request object.
+     */
+    @Deprecated
+    public org.elasticsearch.action.admin.indices.get.GetIndexResponse get(
+            org.elasticsearch.action.admin.indices.get.GetIndexRequest getIndexRequest, RequestOptions options) throws IOException {
+        return restHighLevelClient.performRequestAndParseEntity(getIndexRequest, IndicesRequestConverters::getIndex, options,
+                org.elasticsearch.action.admin.indices.get.GetIndexResponse::fromXContent, emptySet());
+    }
+
+    /**
+     * Retrieve information about one or more indexes
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-get-index.html">
+     * Indices Get Index API on elastic.co</a>
+     * @param getIndexRequest the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @param listener the listener to be notified upon request completion
+     * @deprecated This method uses an old request object which still refers to types, a deprecated feature. The method
+     * {@link #getAsync(GetIndexRequest, RequestOptions, ActionListener)} should be used instead, which accepts a new request object.
+     */
+    @Deprecated
+    public void getAsync(org.elasticsearch.action.admin.indices.get.GetIndexRequest getIndexRequest, RequestOptions options,
+            ActionListener<org.elasticsearch.action.admin.indices.get.GetIndexResponse> listener) {
+        restHighLevelClient.performRequestAsyncAndParseEntity(getIndexRequest, IndicesRequestConverters::getIndex, options,
+                org.elasticsearch.action.admin.indices.get.GetIndexResponse::fromXContent, listener, emptySet());
+    }
+
     /**
      * Force merge one or more indices using the Force Merge API.
      * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-forcemerge.html">
@@ -1058,15 +1093,38 @@ public boolean exists(GetIndexRequest request, RequestOptions options) throws IO
         );
     }
 
+    /**
+     * Checks if the index (indices) exists or not.
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-exists.html">
+     * Indices Exists API on elastic.co</a>
+     * @param request the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @return the response
+     * @throws IOException in case there is a problem sending the request
+     * @deprecated This method uses an old request object which still refers to types, a deprecated feature. The method
+     * {@link #exists(GetIndexRequest, RequestOptions)} should be used instead, which accepts a new request object.
+     */
+    @Deprecated
+    public boolean exists(org.elasticsearch.action.admin.indices.get.GetIndexRequest request, RequestOptions options) throws IOException {
+        return restHighLevelClient.performRequest(
+            request,
+            IndicesRequestConverters::indicesExist,
+            options,
+            RestHighLevelClient::convertExistsResponse,
+            Collections.emptySet()
+        );
+    }
+
     /**
      * Checks if the index (indices) exists or not.
      * <p>
      * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-exists.html">
      * Indices Exists API on elastic.co</a>
-     * @deprecated Prefer {@link #exists(GetIndexRequest, RequestOptions)}
+     * @deprecated This method uses an old request object which still refers to types, a deprecated feature. The method
+     * {@link #exists(GetIndexRequest, RequestOptions)} should be used instead, which accepts a new request object.
      */
     @Deprecated
-    public boolean exists(GetIndexRequest request, Header... headers) throws IOException {
+    public boolean exists(org.elasticsearch.action.admin.indices.get.GetIndexRequest request, Header... headers) throws IOException {
         return restHighLevelClient.performRequest(
                 request,
                 IndicesRequestConverters::indicesExist,
@@ -1095,15 +1153,40 @@ public void existsAsync(GetIndexRequest request, RequestOptions options, ActionL
         );
     }
 
+    /**
+     * Asynchronously checks if the index (indices) exists or not.
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-exists.html">
+     * Indices Exists API on elastic.co</a>
+     * @param request the request
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @param listener the listener to be notified upon request completion
+     * @deprecated This method uses an old request object which still refers to types, a deprecated feature. The method
+     * {@link #existsAsync(GetIndexRequest, RequestOptions, ActionListener)} should be used instead, which accepts a new request object.
+     */
+    @Deprecated
+    public void existsAsync(org.elasticsearch.action.admin.indices.get.GetIndexRequest request, RequestOptions options,
+            ActionListener<Boolean> listener) {
+        restHighLevelClient.performRequestAsync(
+                request,
+                IndicesRequestConverters::indicesExist,
+                options,
+                RestHighLevelClient::convertExistsResponse,
+                listener,
+                Collections.emptySet()
+        );
+    }
+
     /**
      * Asynchronously checks if the index (indices) exists or not.
      * <p>
      * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-exists.html">
      * Indices Exists API on elastic.co</a>
-     * @deprecated Prefer {@link #existsAsync(GetIndexRequest, RequestOptions, ActionListener)}
+     * @deprecated This method uses an old request object which still refers to types, a deprecated feature. The method
+     * {@link #existsAsync(GetIndexRequest, RequestOptions, ActionListener)} should be used instead, which accepts a new request object.
      */
     @Deprecated
-    public void existsAsync(GetIndexRequest request, ActionListener<Boolean> listener, Header... headers) {
+    public void existsAsync(org.elasticsearch.action.admin.indices.get.GetIndexRequest request, ActionListener<Boolean> listener,
+            Header... headers) {
         restHighLevelClient.performRequestAsync(
             request,
             IndicesRequestConverters::indicesExist,

client/rest-high-level/src/main/java/org/elasticsearch/client/IndicesRequestConverters.java

@@ -33,8 +33,6 @@
 import org.elasticsearch.action.admin.indices.flush.FlushRequest;
 import org.elasticsearch.action.admin.indices.flush.SyncedFlushRequest;
 import org.elasticsearch.action.admin.indices.forcemerge.ForceMergeRequest;
-import org.elasticsearch.action.admin.indices.get.GetIndexRequest;
-import org.elasticsearch.client.indices.GetFieldMappingsRequest;
 import org.elasticsearch.action.admin.indices.open.OpenIndexRequest;
 import org.elasticsearch.action.admin.indices.refresh.RefreshRequest;
 import org.elasticsearch.action.admin.indices.rollover.RolloverRequest;
@@ -48,6 +46,8 @@
 import org.elasticsearch.action.support.ActiveShardCount;
 import org.elasticsearch.client.indices.CreateIndexRequest;
 import org.elasticsearch.client.indices.FreezeIndexRequest;
+import org.elasticsearch.client.indices.GetFieldMappingsRequest;
+import org.elasticsearch.client.indices.GetIndexRequest;
 import org.elasticsearch.client.indices.GetIndexTemplatesRequest;
 import org.elasticsearch.client.indices.GetMappingsRequest;
 import org.elasticsearch.client.indices.IndexTemplatesExistRequest;
@@ -151,6 +151,10 @@ static Request putMapping(PutMappingRequest putMappingRequest) throws IOExceptio
         return request;
     }
 
+    /**
+     * converter for the legacy server-side {@link org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest} that still supports
+     * types
+     */
     @Deprecated
     static Request putMapping(org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest putMappingRequest) throws IOException {
         // The concreteIndex is an internal concept, not applicable to requests made over the REST API.
@@ -375,6 +379,28 @@ static Request getSettings(GetSettingsRequest getSettingsRequest) {
         return request;
     }
 
+    /**
+     * converter for the legacy server-side {@link org.elasticsearch.action.admin.indices.get.GetIndexRequest} that
+     * still supports types
+     */
+    @Deprecated
+    static Request getIndex(org.elasticsearch.action.admin.indices.get.GetIndexRequest getIndexRequest) {
+        String[] indices = getIndexRequest.indices() == null ? Strings.EMPTY_ARRAY : getIndexRequest.indices();
+
+        String endpoint = RequestConverters.endpoint(indices);
+        Request request = new Request(HttpGet.METHOD_NAME, endpoint);
+
+        RequestConverters.Params params = new RequestConverters.Params(request);
+        params.withIndicesOptions(getIndexRequest.indicesOptions());
+        params.withLocal(getIndexRequest.local());
+        params.withIncludeDefaults(getIndexRequest.includeDefaults());
+        params.withHuman(getIndexRequest.humanReadable());
+        params.withMasterTimeout(getIndexRequest.masterNodeTimeout());
+        params.putParam(INCLUDE_TYPE_NAME_PARAMETER, Boolean.TRUE.toString());
+
+        return request;
+    }
+
     static Request getIndex(GetIndexRequest getIndexRequest) {
         String[] indices = getIndexRequest.indices() == null ? Strings.EMPTY_ARRAY : getIndexRequest.indices();
 
@@ -388,11 +414,33 @@ static Request getIndex(GetIndexRequest getIndexRequest) {
         params.withHuman(getIndexRequest.humanReadable());
         params.withMasterTimeout(getIndexRequest.masterNodeTimeout());
         // Force "include_type_name" parameter since responses need to be compatible when coming from 7.0 nodes
-        params.withIncludeTypeName(true);
+        params.putParam(INCLUDE_TYPE_NAME_PARAMETER, Boolean.FALSE.toString());
 
         return request;
     }
 
+    /**
+     * converter for the legacy server-side {@link org.elasticsearch.action.admin.indices.get.GetIndexRequest} that
+     * still supports types
+     */
+    @Deprecated
+    static Request indicesExist(org.elasticsearch.action.admin.indices.get.GetIndexRequest getIndexRequest) {
+        // this can be called with no indices as argument by transport client, not via REST though
+        if (getIndexRequest.indices() == null || getIndexRequest.indices().length == 0) {
+            throw new IllegalArgumentException("indices are mandatory");
+        }
+        String endpoint = RequestConverters.endpoint(getIndexRequest.indices(), "");
+        Request request = new Request(HttpHead.METHOD_NAME, endpoint);
+
+        RequestConverters.Params params = new RequestConverters.Params(request);
+        params.withLocal(getIndexRequest.local());
+        params.withHuman(getIndexRequest.humanReadable());
+        params.withIndicesOptions(getIndexRequest.indicesOptions());
+        params.withIncludeDefaults(getIndexRequest.includeDefaults());
+        params.putParam(INCLUDE_TYPE_NAME_PARAMETER, Boolean.TRUE.toString());
+        return request;
+    }
+
     static Request indicesExist(GetIndexRequest getIndexRequest) {
         // this can be called with no indices as argument by transport client, not via REST though
         if (getIndexRequest.indices() == null || getIndexRequest.indices().length == 0) {
@@ -406,6 +454,7 @@ static Request indicesExist(GetIndexRequest getIndexRequest) {
         params.withHuman(getIndexRequest.humanReadable());
         params.withIndicesOptions(getIndexRequest.indicesOptions());
         params.withIncludeDefaults(getIndexRequest.includeDefaults());
+        params.putParam(INCLUDE_TYPE_NAME_PARAMETER, Boolean.FALSE.toString());
         return request;
     }
 

client/rest-high-level/src/main/java/org/elasticsearch/client/indices/GetIndexRequest.java

@@ -0,0 +1,132 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.client.indices;
+
+import org.elasticsearch.action.support.IndicesOptions;
+import org.elasticsearch.client.TimedRequest;
+import org.elasticsearch.common.util.ArrayUtils;
+
+/**
+ * A request to retrieve information about an index.
+ */
+public class GetIndexRequest extends TimedRequest {
+
+    public enum Feature {
+        ALIASES,
+        MAPPINGS,
+        SETTINGS;
+    }
+
+    static final Feature[] DEFAULT_FEATURES = new Feature[] { Feature.ALIASES, Feature.MAPPINGS, Feature.SETTINGS };
+    private Feature[] features = DEFAULT_FEATURES;
+    private boolean humanReadable = false;
+    private transient boolean includeDefaults = false;
+
+    private final String[] indices;
+    private IndicesOptions indicesOptions = IndicesOptions.fromOptions(false, false, true, true);
+    private boolean local = false;
+
+    public GetIndexRequest(String... indices) {
+        this.indices = indices;
+    }
+
+    /**
+     * The indices into which the mappings will be put.
+     */
+    public String[] indices() {
+        return indices;
+    }
+
+    public IndicesOptions indicesOptions() {
+        return indicesOptions;
+    }
+
+    public GetIndexRequest indicesOptions(IndicesOptions indicesOptions) {
+        this.indicesOptions = indicesOptions;
+        return this;
+    }
+
+    public final GetIndexRequest local(boolean local) {
+        this.local = local;
+        return this;
+    }
+
+    /**
+     * Return local information, do not retrieve the state from master node (default: false).
+     * @return <code>true</code> if local information is to be returned;
+     * <code>false</code> if information is to be retrieved from master node (default).
+     */
+    public final boolean local() {
+        return local;
+    }
+
+    public GetIndexRequest features(Feature... features) {
+        if (features == null) {
+            throw new IllegalArgumentException("features cannot be null");
+        } else {
+            this.features = features;
+        }
+        return this;
+    }
+
+    public GetIndexRequest addFeatures(Feature... features) {
+        if (this.features == DEFAULT_FEATURES) {
+            return features(features);
+        } else {
+            return features(ArrayUtils.concat(features(), features, Feature.class));
+        }
+    }
+
+    public Feature[] features() {
+        return features;
+    }
+
+    public GetIndexRequest humanReadable(boolean humanReadable) {
+        this.humanReadable = humanReadable;
+        return this;
+    }
+
+    public boolean humanReadable() {
+        return humanReadable;
+    }
+
+    /**
+     * Sets the value of "include_defaults".
+     *
+     * @param includeDefaults value of "include_defaults" to be set.
+     * @return this request
+     */
+    public GetIndexRequest includeDefaults(boolean includeDefaults) {
+        this.includeDefaults = includeDefaults;
+        return this;
+    }
+
+    /**
+     * Whether to return all default settings for each of the indices.
+     *
+     * @return <code>true</code> if defaults settings for each of the indices need to returned;
+     * <code>false</code> otherwise.
+     */
+    public boolean includeDefaults() {
+        return includeDefaults;
+    }
+
+
+}