docs: public static int writeAsciiString(byte[] array, int startPos, String attribute) {
          Preconditions.checkArgument(isAsciiString(attribute));
          if (attribute.length()==0) {
              array[startPos++] = (byte)0x80;
          } else {
              for (int i = 0; i < attribute.length(); i++) {
                  int c = attribute.charAt(i);
                  assert c <= 127;
                  byte b = (byte)c;
                  if (i+1==attribute.length()) b |= 0x80; //End marker
                  array[startPos++]=b;
              }
          }
          return startPos;
      }