code: public static byte[] externalize(byte[] buf, int offset, int len) {
          byte[] translated = new byte[len];
          for (int j = 0; j < len; j++) {
              byte b = buf[offset + j];
              if (b == '.') translated[j] = (byte) '/';
              else translated[j] = b;
          }
          return translated;
      }
docs: Return external representation of buf[offset..offset+len-1], converting '.' to '/'.
  
  Note: the naming is the inverse of that used by JVMS 4.2 The Internal Form Of Names,
  which defines "internal name" to be the form using "/" instead of "."