Groups from Box API

I have a user, which is a co-admin to manage Users and Groups.

Via Box UI, I can add groups as collaborator for a folder, I have access to all groups.

Via Box API, when I list the groups of the enterprise, with this same user, I receive an empty list as a response.

As you can see, for a specific group, I should be able to see it:

Every time, I receive this response from the API:

https://api.box.com/2.0/groups
200
{"total_count":0,"entries":[],"limit":100,"offset":0}

Is there any other access rights that I should set?

From the administration UI I have lots of groups (5 pages), so why is the result empty?

My code:

String strToken = "";
		
		String URL = "https://api.box.com/2.0/groups" ;

		System.out.println(URL);

		HttpURLConnection connection = null;
		try {
			connection = (HttpURLConnection) new URL(URL).openConnection();
			connection.setRequestMethod("GET");
			connection.addRequestProperty("Authorization", "Bearer " + strToken);
			connection.addRequestProperty("Accept-Charset", "utf-8");
			connection.addRequestProperty("Content-Type", "application/json");
			connection.connect();

			int status = connection.getResponseCode();
			System.out.println(status);

			int BUFFER_SIZE = 8192;
			InputStreamReader input = new InputStreamReader(connection.getInputStream());
			StringBuilder builder = new StringBuilder();
			char[] buffer = new char[BUFFER_SIZE];

			try {
				int read = input.read(buffer, 0, BUFFER_SIZE);
				while (read != -1) {
					builder.append(buffer, 0, read);
					read = input.read(buffer, 0, BUFFER_SIZE);
				}
				input.close();
			} catch (IOException e) {
				System.out.println(e.getStackTrace());
			}

			String jsonText = builder.toString();
			System.out.println(jsonText);

			connection.disconnect();

		} catch (IOException e) {
			System.out.println(e.getMessage());
			e.printStackTrace();
		}