Spring Reactive + Okta + Access token

Questions
1

I am using Spring Reactive to get access token for a registered OKTA app. I have Client Id and Secret with me along with the URI.
I would like to know how to get access token from the client Id and secret.

2

I don’t need the API hit approach here, please provide me some classes which can be used here like application context classes.
If possible, provide URL for reference.

3

This blog post shows you how to get an access token:

package com.oktadeveloper.graphqldemo;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.oauth2.client.OAuth2AuthorizedClient;
import org.springframework.security.oauth2.client.OAuth2AuthorizedClientService;
import org.springframework.security.oauth2.client.authentication.OAuth2AuthenticationToken;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.security.Principal;

@RestController
class MyAccessTokenController {

    @Autowired
    private OAuth2AuthorizedClientService clientService;

    @RequestMapping("/my-access-token")
    String home(Principal user) {
        OAuth2AuthenticationToken token = (OAuth2AuthenticationToken) user;
        String authorizedClientRegistrationId = token.getAuthorizedClientRegistrationId();
        String name = user.getName();
        OAuth2AuthorizedClient client = clientService.loadAuthorizedClient(authorizedClientRegistrationId, name);
        return "token: " + client.getAccessToken().getTokenValue();
    }

}
4

I don’t have a client, it should be server to server communication. My program has to create a token and not through API calls. I need to use only spring security classes to generate it. Probably a dependency from Okta for spring boot is what I needed. With article if possible.