public void setCredentialsAuthExtras(final Intent intent) {
            if (intent != null) {
                intent.putExtra(Intents.EXTRA_CREDENTIALS_AUTH_USERNAME, StringUtils.defaultIfBlank(username, StringUtils.EMPTY));
                intent.putExtra(Intents.EXTRA_CREDENTIALS_AUTH_PASSWORD, StringUtils.defaultIfBlank(password, StringUtils.EMPTY));
            }
        }
Enable or disable the start button depending on login/password field.
If both fields are not empty, button is enabled.
main/src/main/java/cgeo/geocaching/settings/AbstractCredentialsAuthorizationActivity.java