code: public void setHeaders(Map<String, String> map) {
          headers = new MetadataMap<String, String>();
          for (Map.Entry<String, String> entry : map.entrySet()) {
              String[] values = entry.getValue().split(",");
              for (String v : values) {
                  if (v.length() != 0) {
                      headers.add(entry.getKey(), v);
                  }
              }
          }
      }
docs: Sets the headers new proxy or WebClient instances will be
  initialized with.
  
  @param map the headers