Downgrade to Java 11.

Downgrades to Java 11 in order to support consumers that are not on
Java 16 yet.

Change-Id: Ia5930d1c40d0090ca145fd14c0b63a139e4ac970
diff --git a/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java b/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
index 0c691b7..d2e5562 100644
--- a/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
+++ b/runtime/src/main/java/eu/mulk/quarkus/googlecloud/jsonlogging/Formatter.java
@@ -36,9 +36,10 @@
     Map<String, String> labels = new HashMap<>();
     if (logRecord.getParameters() != null) {
       for (var parameter : logRecord.getParameters()) {
-        if (parameter instanceof StructuredParameter sparam) {
-          parameters.add(sparam);
-        } else if (parameter instanceof Label label) {
+        if (parameter instanceof StructuredParameter) {
+          parameters.add((StructuredParameter) parameter);
+        } else if (parameter instanceof Label) {
+          var label = (Label) parameter;
           labels.put(label.key(), label.value());
         }
       }