code: public HttpHubConnectionBuilder withHeader(String name, String value) {
          if (headers == null) {
              this.headers = new HashMap<>();
          }
          this.headers.put(name, value);
          return this;
      }
docs: Sets a single header for the {@link HubConnection} to send.
  
  @param name The name of the header to set.
  @param value The value of the header to be set.
  @return This instance of the HttpHubConnectionBuilder.