code: public List<Namespace> getNamespaces(int page, int perPage) throws GitLabApiException {
          Response response = get(Response.Status.OK, getPageQueryParams(page, perPage), "namespaces");
          return (response.readEntity(new GenericType<List<Namespace>>() {}));
      }
docs: Get a list of the namespaces of the authenticated user. If the user is an administrator,
  a list of all namespaces in the GitLab instance is returned.
  
  <pre><code>GitLab Endpoint: GET /namespaces</code></pre>
  
  @param page the page to get
  @param perPage the number of Namespace instances per page
  @return a List of Namespace instances in the specified page range
  @throws GitLabApiException if any exception occurs