polish

Author: jan-elastic

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/grouping/Categorize.java

@@ -36,6 +36,7 @@
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 import static java.util.Map.entry;
@@ -185,7 +186,7 @@ public CategorizeDef categorizeDef() {
         String outputFormatString = (String) optionsMap.get("output_format");
         if (outputFormatString != null) {
             try {
-                outputFormat = OutputFormat.valueOf(outputFormatString.toUpperCase());
+                outputFormat = OutputFormat.valueOf(outputFormatString.toUpperCase(Locale.ROOT));
             } catch (IllegalArgumentException e) {
                 throw new InvalidArgumentException(
                     format(null, "invalid output format [{}], expecting one of [REGEX, TOKENS]", outputFormatString)