[ML] fix grabbing the doc value limit setting in _explain (#63402)

Getting the doc value settings shouldn't use the API callers headers. We only use this value internally.

x-pack/plugin/ml/qa/native-multi-node-tests/src/javaRestTest/java/org/elasticsearch/xpack/ml/integration/ExplainDataFrameAnalyticsRestIT.java

@@ -117,8 +117,7 @@ public class ExplainDataFrameAnalyticsRestIT extends ESRestTestCase {
             addSecondaryAuthHeader(options, ML_ADMIN);
             explain.setOptions(options);
             // Should throw
-            ResponseException ex = expectThrows(ResponseException.class, () -> client().performRequest(explain));
-            assertThat(ex.getResponse().getStatusLine().getStatusCode(), equalTo(403));
+            expectThrows(ResponseException.class, () -> client().performRequest(explain));
         }
         { // request with secondary headers with perms
             Request explain = explainRequestViaConfig(config);
@@ -160,8 +159,7 @@ public class ExplainDataFrameAnalyticsRestIT extends ESRestTestCase {
             addSecondaryAuthHeader(options, ML_ADMIN);
             explain.setOptions(options);
             // Should throw
-            ResponseException ex = expectThrows(ResponseException.class, () -> client().performRequest(explain));
-            assertThat(ex.getResponse().getStatusLine().getStatusCode(), equalTo(403));
+            expectThrows(ResponseException.class, () -> client().performRequest(explain));
         }
         { // request with secondary headers with perms
             Request explain = explainRequestConfigId(configId);

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/ExtractedFieldsDetector.java

@@ -376,8 +376,10 @@ public class ExtractedFieldsDetector {
         if (preferSource) {
             extractedFields = fetchFromSourceIfSupported(extractedFields);
             if (extractedFields.getDocValueFields().size() > docValueFieldsLimit) {
-                throw ExceptionsHelper.badRequestException("[{}] fields must be retrieved from doc_values but the limit is [{}]; " +
-                        "please adjust the index level setting [{}]", extractedFields.getDocValueFields().size(), docValueFieldsLimit,
+                throw ExceptionsHelper.badRequestException(
+                    "[{}] fields must be retrieved from doc_values and this is greater than the configured limit. " +
+                        "Please adjust the index level setting [{}]",
+                    extractedFields.getDocValueFields().size(),
                     IndexSettings.MAX_DOCVALUE_FIELDS_SEARCH_SETTING.getKey());
             }
         }

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/dataframe/extractor/ExtractedFieldsDetectorFactory.java

@@ -11,6 +11,7 @@ import org.apache.logging.log4j.Logger;
 import org.apache.logging.log4j.message.ParameterizedMessage;
 import org.elasticsearch.ResourceNotFoundException;
 import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.admin.indices.settings.get.GetSettingsAction;
 import org.elasticsearch.action.admin.indices.settings.get.GetSettingsRequest;
 import org.elasticsearch.action.admin.indices.settings.get.GetSettingsResponse;
 import org.elasticsearch.action.fieldcaps.FieldCapabilities;
@@ -45,6 +46,9 @@ import java.util.Objects;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
 
+import static org.elasticsearch.xpack.core.ClientHelper.ML_ORIGIN;
+import static org.elasticsearch.xpack.core.ClientHelper.executeAsyncWithOrigin;
+
 /**
  * A factory that retrieves all the parts necessary to build a {@link ExtractedFieldsDetector}.
  */
@@ -138,7 +142,7 @@ public class ExtractedFieldsDetectorFactory {
         }
         SearchRequest searchRequest = new SearchRequest(index).source(searchSourceBuilder);
         ClientHelper.executeWithHeadersAsync(
-            config.getHeaders(), ClientHelper.ML_ORIGIN, client, SearchAction.INSTANCE, searchRequest, searchListener);
+            config.getHeaders(), ML_ORIGIN, client, SearchAction.INSTANCE, searchRequest, searchListener);
     }
 
     private void buildFieldCardinalitiesMap(DataFrameAnalyticsConfig config, SearchResponse searchResponse,
@@ -168,7 +172,7 @@ public class ExtractedFieldsDetectorFactory {
         fieldCapabilitiesRequest.fields("*");
         LOGGER.debug(() -> new ParameterizedMessage(
             "[{}] Requesting field caps for index {}", config.getId(), Arrays.toString(index)));
-        ClientHelper.executeWithHeaders(config.getHeaders(), ClientHelper.ML_ORIGIN, client, () -> {
+        ClientHelper.executeWithHeaders(config.getHeaders(), ML_ORIGIN, client, () -> {
             client.execute(FieldCapabilitiesAction.INSTANCE, fieldCapabilitiesRequest, listener);
             // This response gets discarded - the listener handles the real response
             return null;
@@ -205,6 +209,6 @@ public class ExtractedFieldsDetectorFactory {
         getSettingsRequest.indices(index);
         getSettingsRequest.includeDefaults(true);
         getSettingsRequest.names(IndexSettings.MAX_DOCVALUE_FIELDS_SEARCH_SETTING.getKey());
-        client.admin().indices().getSettings(getSettingsRequest, settingsListener);
+        executeAsyncWithOrigin(client, ML_ORIGIN, GetSettingsAction.INSTANCE, getSettingsRequest, settingsListener);
     }
 }