Return null from getRepositoryURL when no remotes; skip writing repository key in serializer

Agent-Logs-Url: https://github.com/getappmap/appmap-java/sessions/9269e403-28ed-4394-be5f-17ca657e822a

Co-authored-by: kgilpin <86395+kgilpin@users.noreply.github.com>

Author: Copilot

agent/src/main/java/com/appland/appmap/record/AppMapSerializer.java

@@ -185,8 +185,11 @@ private void writeMetadata(GitUtil git, Metadata metadata) throws IOException {
         this.json.writeKey("git");
         this.json.startObject();
         {
-          this.json.writeKey("repository");
-          this.json.writeValue(git.getRepositoryURL());
+          String repositoryURL = git.getRepositoryURL();
+          if (repositoryURL != null) {
+            this.json.writeKey("repository");
+            this.json.writeValue(repositoryURL);
+          }
           this.json.writeKey("branch");
           this.json.writeValue(git.getBranch());
           this.json.writeKey("commit");

agent/src/main/java/com/appland/appmap/util/GitUtil.java

@@ -100,19 +100,19 @@ public String getRepositoryURL() {
     try {
       List<RemoteConfig> remotes = git.remoteList().call();
       if (remotes.isEmpty()) {
-        return "";
+        return null;
       }
       Optional<RemoteConfig> originConfig = remotes.stream().filter(r -> r.getName().equals("origin")).findFirst();
       RemoteConfig remote = originConfig.orElseGet(() -> remotes.get(0));
       List<URIish> uris = remote.getURIs();
       if (uris.isEmpty()) {
-        return "";
+        return null;
       }
       return uris.get(0).toASCIIString();
     } catch (GitAPIException e) {
       logger.warn(e);
     }
-    return "";
+    return null;
   }
 
   public String getBranch() {