title: Getting INVALID_COUNTRY_CODE exception when trying to parse phone number without country code
body: <p>I am using libphonenumber jar (version 7) and trying to parse phone number without setting Region. I saw following code as recommended. </p>
  
  <pre><code>PhoneNumber phoneNumber = phoneUtil.parse(numberStr, ""));
  </code></pre>
  
  <p>However, this is throwing INVALID_COUNTRY_CODE exception. Did something change in the latest version? How can I get region code (US) for given number like ("+1-xxx-xxx-xxxx")?</p>