Operator '+' cannot be applied to 'java.lang.String', 'void' intellij maven

im trying to make test scenario but im getting this error searched other questions before but still didint find and anserw pls help

StepDefs:

 @Given("i check if comment exsist")
    public void checkPost() throws IOException,URISyntaxException {
        final URL url = new URL("http://localhost:3000/comments/" + networkConfigurationProperties.lastPath());
        HttpURLConnection huc = (HttpURLConnection) url.openConnection();
        int responseCode = huc.getResponseCode();
        if (responseCode == 200) {
            System.out.println("comment exist");
        } else {
            System.out.println("comment doesn't exist");
        }
    }

NetworkConfigurationProperties:
public class NetworkConfigurationProperties {
    public void lastPath() throws IOException,URISyntaxException {
        final URI uri = new URI("http://localhost:3000/comments/");
        String path = uri.getPath();
        String idStr = path.substring(path.lastIndexOf('/') + 1);
        int id = Integer.parseInt(idStr);


    }