[TEST] add test to ensure legacy list syntax in yml works fine

core/src/test/java/org/elasticsearch/common/settings/SettingsTests.java

@@ -35,6 +35,8 @@ import org.hamcrest.CoreMatchers;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.io.StringBufferInputStream;
+import java.io.StringReader;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -618,6 +620,15 @@ public class SettingsTests extends ESTestCase {
         assertThat(settings.getAsArray("test1.test3")[1], equalTo("test3-2"));
     }
 
+    public void testYamlLegacyList() throws IOException {
+        Settings settings = Settings.builder()
+            .loadFromStream("foo.yml", new ByteArrayInputStream("foo.bar.baz.0: 1\nfoo.bar.baz.1: 2".getBytes(StandardCharsets.UTF_8)),
+                false).build();
+        assertThat(settings.getAsArray("foo.bar.baz").length, equalTo(2));
+        assertThat(settings.getAsArray("foo.bar.baz")[0], equalTo("1"));
+        assertThat(settings.getAsArray("foo.bar.baz")[1], equalTo("2"));
+    }
+
     public void testIndentation() throws Exception {
         String yaml = "/org/elasticsearch/common/settings/loader/indentation-settings.yml";
         ElasticsearchParseException e = expectThrows(ElasticsearchParseException.class, () -> {