apollo-core/src/main/java/com/ctrip/framework/foundation/internals/io/BOMInputStream.java/BOMInputStream/compare
class BOMInputStream:    public int compare(final ByteOrderMark bom1, final ByteOrderMark bom2) {
      final int len1 = bom1.length();
      final int len2 = bom2.length();
      if (len1 > len2) {
        return EOF;
      }
      if (len2 > len1) {
        return 1;
      }
      return 0;
    }