title: How can I pass void *payload object in git_index_add_all() method of libgit2 library?
body: <p>I am running libgit2 v0.23.0. I am calling method <a href="https://libgit2.github.com/libgit2/#v0.23.0/group/index/git_index_add_all" rel="nofollow">git_index_add_all</a> which takes following parameters:  </p>
  
  <ul>
  <li>git_index * index </li>
  <li>const git_strarray * pathspec </li>
  <li>unsigned int     flags   </li>
  <li>git_index_matched_path_cb    callback     </li>
  <li>void *   payload</li>
  </ul>
  
  <p>I am not able to get how do I need to create last <code>void *payload parameter</code> </p>
  
  <p>My code is :  </p>
  
  <pre><code> git_index *idx = NULL;
   git_index_matched_path_cb matched_cb = NULL;
   int error = 0;
   error = git_index_open(&amp;idx, "repofolder/.git/index");
   char *paths[] = {"repofolder/*"};
   git_strarray arr = {paths, 1};
   error = git_index_add_all(idx, &amp;arr, GIT_INDEX_ADD_DEFAULT,matched_cb, ?);
  </code></pre>
  
  <p>could anybody suggest me, what should be way to create or get payload type object ?</p>