Temporary fix for MultiParagraph fields

The Mongo simplification code removes the paragraphs field if it's an
empty array, but there's code in LexEntryModel (generateCustomField)
that does the wrong thing when the paragraphs field is absent. That code
will eventually use the type field to detect MultiParagraphs, but until
the type field is in use everywhere, we still need to keep the
paragraphs field around.


Former-commit-id: 11dba43

src/Api/Model/Shared/Mapper/MongoMapper.php

@@ -395,7 +395,7 @@ public static function shouldPersist($value) {
 
     public static function shouldKeepKey(string $key) {
         // Some keys shouldn't be removed even if empty, at least as long as our code is still making assumptions that these keys exist
-        return ($key === "guid" || $key === "translation" || $key === "description" || $key === "answers");
+        return ($key === "guid" || $key === "translation" || $key === "description" || $key === "answers" || $key == "paragraphs");
     }
 
     public static function removeEmptyItems(array $array) {