Only emit product origin in deprecation log if present (#111683)

The elastic product origin may not always be present when deprecation
messages are emitted. This commit changes the log message created for
deprecations to only emit the product origin field if it is not empty.

closes #81757

docs/changelog/111683.yaml

@@ -0,0 +1,6 @@
+pr: 111683
+summary: Only emit product origin in deprecation log if present
+area: Infra/Logging
+type: bug
+issues:
+ - 81757

server/src/main/java/org/elasticsearch/common/logging/DeprecatedMessage.java

@@ -62,10 +62,12 @@ public class DeprecatedMessage {
             .field(KEY_FIELD_NAME, key)
             .field("elasticsearch.event.category", category.name().toLowerCase(Locale.ROOT));
 
-        if (Strings.isNullOrEmpty(xOpaqueId)) {
-            return esLogMessage;
+        if (Strings.isNullOrEmpty(xOpaqueId) == false) {
+            esLogMessage.field(X_OPAQUE_ID_FIELD_NAME, xOpaqueId);
         }
-
-        return esLogMessage.field(X_OPAQUE_ID_FIELD_NAME, xOpaqueId).field(ELASTIC_ORIGIN_FIELD_NAME, productOrigin);
+        if (Strings.isNullOrEmpty(productOrigin) == false) {
+            esLogMessage.field(ELASTIC_ORIGIN_FIELD_NAME, productOrigin);
+        }
+        return esLogMessage;
     }
 }