java.io.FileNotFoundException: file:{localpath}application.jar!BOOT-INFclasses!application.properties (The filename, directory name, or volume label syntax is incorrect)

username=user
password=password123

//get properties
    prop = new Properties();
    InputStream input = null;
    try {
        input = new FileInputStream(f);
        // load a properties file
        prop.load(input);
    } catch (IOException ex) {
        logger.error("Error reading application.properties", ex);
        ex.printStackTrace();
    } finally {
        if (input != null) {
            try {
                input.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    //update properties
    prop.setProperty("TESTSTRING", "testvalue");

    //write to properties file
    OutputStream os = null;
    try{
        File f = new File(Application.class.getClassLoader().getResource("application.properties").getFile());
        os = new FileOutputStream(f);
        prop.store(os, comments);
    }catch(IOException ex){
        logger.error("Error updating application.properties", ex);
        ex.printStackTrace();
    } finally {
        if(os != null){
            try{
                os.close();
            } catch (IOException e){
                e.printStackTrace();
            }
        }