code: private HeaderEntry getEntry(byte[] name, byte[] value) {
      if (length() == 0 || name == null || value == null) {
        return null;
      }
      int h = hash(name);
      int i = index(h);
      for (HeaderEntry e = headerFields[i]; e != null; e = e.next) {
        if (e.hash == h &&
            HpackUtil.equals(name, e.name) &&
            HpackUtil.equals(value, e.value)) {
          return e;
        }
      }
      return null;
    }
docs: Returns the header entry with the lowest index value for the header field.
  Returns null if header field is not in the dynamic table.