fix compile

Author: davidkyle

x-pack/qa/src/main/java/org/elasticsearch/xpack/test/rest/IndexMappingTemplateAsserter.java

@@ -120,7 +120,7 @@ public static void assertTemplateVersionAndPattern(RestClient client, String tem
             "index_templates",
             "index_template",
             "version"
-        )).getFirst();
+        )).get(0);
         assertEquals(version, templateVersion.intValue());
 
         var templateIndexPatterns = ((List<String>) XContentMapValues.extractValue(