code: public Response andHeaders(Map<HttpString, String> headers) {
          Objects.requireNonNull(headers, Required.HEADERS.toString());
          this.headers.putAll(headers);
  
          return this;
      }
docs: Adds an additional header map to the response.
  Already existing values with the same key are overwritten.
  
  @param headers The headers map to add
  @return A response object {@link io.mangoo.routing.Response}