Can't issue an HTTP request to my Apache2 local server within my IDE

I’ve just installed Apache2 on my Ubuntu machine and I’ve created a simple HTML (Hello World message) page within the dedicated directory for such content:

/var/www/html/example/index.html

I’m able to see the "Hello Word" message on my browser (Firefox). I used the common URL to perform this kind of operation:

http://127.0.0.1/example/index.html

It works well!

but when I’m trying to do the same request with some Java code it only return me a 400 error:

HTTP/1.1 400 Bad Request
Date: Wed, 21 Oct 2020 15:45:21 GMT
Server: Apache/2.4.41 (Ubuntu)
Content-Length: 301
Connection: close
Content-Type: text/html; charset=iso-8859-1

My Java code looks like this:

public static void main(String[] args) throws UnknownHostException, IOException {
          // The host and port to be connected.
      String host = "127.0.0.1";
      int port = 80;
      // Create a TCP socket and connect to the host:port.
      Socket socket = new Socket(host, port);
      // Create the input and output streams for the network socket.
      BufferedReader in
         = new BufferedReader(
              new InputStreamReader(socket.getInputStream()));
      PrintWriter out
         = new PrintWriter(socket.getOutputStream(), true);
      // Send request to the HTTP server.
      out.println("GET /example/index.html HTTP/1.1");
      out.println("Host: 127.0.0.1");
      out.println();   // blank line separating header & body
      out.flush();
      // Read the response and display on console.
      String line;
      // readLine() returns null if server close the network socket.
      while((line = in.readLine()) != null) {
         System.out.println(line);
      }
      // Close the I/O streams.
      in.close();
      out.close();

Can someone help me?