for (int i = 1; key != null || value != null; i++) {
            List values = (List) map.get(key);
            if (values == null) {
                values = new ArrayList();
                map.put(key, values);
            }
            values.add(value);
            key = connection.getHeaderFieldKey(i);
            value = connection.getHeaderField(i);
        }

        for ( int i = 1; key != null || value != null; i++ ) {
            List<String> values = map.get(key);
            if ( values == null ) {
                values = new ArrayList<>();
                map.put(key, values);
            }
            values.add(value);
            key = this.connection.getHeaderFieldKey(i);
            value = this.connection.getHeaderField(i);
        }