Scripts: Convert template script engines to return String instead of BytesReference (#24447)

Template script engines (mustache, the only one) currently return a
BytesReference that users must know is utf8 encoded. This commit
modifies all callers and mustache to have the template engine return
String. This is much simpler, and does not require decoding in order to
use (for example, in ingest).

1 files changed, 1 insertions, 1 deletions

diff --git a/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggester.java b/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggester.java
index fc862f6363..9e9e2c66f7 100644
--- a/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggester.java
+++ b/core/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggester.java
@@ -116,7 +116,7 @@ public final class PhraseSuggester extends Suggester<PhraseSuggestionContext> {
                     vars.put(SUGGESTION_TEMPLATE_VAR_NAME, spare.toString());
                     QueryShardContext shardContext = suggestion.getShardContext();
                     final ExecutableScript executable = collateScript.apply(vars);
-                    final BytesReference querySource = (BytesReference) executable.run();
+                    final String querySource = (String) executable.run();
                     try (XContentParser parser = XContentFactory.xContent(querySource).createParser(shardContext.getXContentRegistry(),
                             querySource)) {
                         QueryBuilder innerQueryBuilder = shardContext.newParseContext(parser).parseInnerQueryBuilder();