code: public WikiPage updatePage(Object projectIdOrPath, String slug, String title, String content) throws GitLabApiException {
  
          GitLabApiForm formData = new GitLabApiForm()
                  .withParam("title", title)
                  .withParam("slug", slug, true)
                  .withParam("content", content);
  
          Response response = put(Response.Status.OK, formData.asMap(), "projects", getProjectIdOrPath(projectIdOrPath), "wikis", slug);
          return (response.readEntity(WikiPage.class));
      }
docs: Updates an existing project wiki page. The user must have permission to change an existing wiki page.
  
  <pre><code>GitLab Endpoint: PUT /projects/:id/wikis/:slug</code></pre>
  
  @param projectIdOrPath the project in the form of an Integer(ID), String(path), or Project instance
  @param slug the slug of the project's wiki page, required
  @param title the title of a snippet, optional
  @param content the content of a page, optional. Either title or content must be supplied.
  @return a WikiPage instance with info on the updated page
  @throws GitLabApiException if any exception occurs