Fix isPublished decoder

src/main/kotlin/RecordSetSearchDocBuilder.kt

@@ -58,6 +58,7 @@ class RecordSetSearchDocBuilder(private val elasticSearchWrapper: ElasticSearchW
                 recordSetId = id,
                 isPublished = recordSet[KEYS.isPublished].let {
                     when (it) {
+                        is Boolean -> it
                         is String -> it.toBoolean()
                         else -> {
                             log.error("Found no isPublished property on record set $key. Set to false.")