code: public List<HeaderEntry> getHeaderEntryList() {
      final List<HeaderEntry> list = new ArrayList<>();
      final Iterator it = this.headers.entrySet().iterator();
      while (it.hasNext()) {
        final Map.Entry pair = (Map.Entry)it.next();
        System.out.println(pair.getKey() + " = " + pair.getValue());
        final HeaderEntry e = HeaderEntry.newBuilder()
                .setKey((String) pair.getKey())
                .setValue((String) pair.getValue())
                .build();
        list.add(e);
        it.remove(); // avoids a ConcurrentModificationException
      }
      return list;
    }
docs: get http header as a list of HeaderEntry.
  @return