[FINNA-4570] Add container_title_str_mv field

conf/recordmanager.ini.sample.finna

@@ -27,3 +27,8 @@
 ; Example for allowing IIIF json files.
 ;allowed_media_types[] = application/ld+json;profile="http://iiif.io/api/presentation/3/context.json"
 
+; The following section can be used to change the Solr fields used when indexing
+; records, particularly for hierarchical records. Any field can also be set to empty
+; to disable it.
+;[Solr Fields]
+;container_title_facet = 

src/RecordManager/Finna/Solr/SolrUpdater.php

@@ -31,6 +31,7 @@
 
 use RecordManager\Base\Record\AbstractRecord;
 
+use function in_array;
 use function intval;
 use function is_callable;
 use function strlen;
@@ -73,6 +74,19 @@ protected function augmentAndProcessFields(
                 $data['catalog_date'] = $date;
             }
         }
+        if (
+            $containerTitleFacetField = $this->config['Solr Fields']['container_title_facet']
+                ?? 'container_title_str_mv'
+        ) {
+            // Use hierarchy_top_title for ead and ead3 formats instead of hierarchy_parent_title.
+            if (in_array($record['format'], ['ead', 'ead3'])) {
+                if (isset($data['hierarchy_top_title'])) {
+                    $data[$containerTitleFacetField] = (array)$data['hierarchy_top_title'];
+                }
+            } elseif ($this->hierarchyParentTitleField && isset($data[$this->hierarchyParentTitleField])) {
+                $data[$containerTitleFacetField] = (array)$data[$this->hierarchyParentTitleField];
+            }
+        }
         $this->addSeriesKeys($data, $metadataRecord);
     }