protected static VersionNumber parseVersionNumber(@Nonnull String versionString){
  Matcher matcher=pattern.matcher(versionString.trim());
  if (matcher.matches()) {
    String major=matcher.group(2);
    String minor=matcher.group(3);
    String maint=matcher.group(4);
    return new VersionNumber(String.format("%s.%s.%s",major,minor,maint));
  }
 else {
    return null;
  }
}

protected static VersionNumber parseVersionNumber ( @ Nonnull String versionString ) { Matcher matcher = pattern . matcher ( versionString . trim ( ) ) ; if ( matcher . matches ( ) ) { String major = matcher . group ( 2 ) ; String minor = matcher . group ( 3 ) ; String maint = matcher . group ( 4 ) ; return new VersionNumber ( String . format ( "%s.%s.%s" , major , minor , maint ) ) ; } else { return null ; } }
parse a docker version string ( e . g . " docker version 1 . 5 . 0 , build a8a31ef " ) .
