import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;

public class Main {

    public static void main(String... args) throws IOException {
        
        String email = "YOUR_EMAIL_HERE";
        String token = "YOUR_TOKEN_HERE";
        String projectCode = "YOUR_PROJECT_CODE_HERE";
        long amount = 1000L; //minimum 10 rub!

        JSONObject request = new JSONObject();
        request.put("projectCode", projectCode);
        request.put("description", "its easy, man!");
        JSONObject amountObject = new JSONObject();
        amountObject.put("amount", amount);
        amountObject.put("currency", "RUB");
        request.put("amount", amountObject);

        URL url = new URL("https://api.capusta.space/v1/partner/payment"); // payment url
        HttpURLConnection con = (HttpURLConnection) url.openConnection();
        con.setDoOutput(true);
        con.setRequestMethod("POST");
        con.setRequestProperty("Content-Type", "application/json; utf-8");
        con.setRequestProperty("Authorization", "Bearer " + email + ":" + token);
        
        try(OutputStream os = con.getOutputStream()) {
            byte[] input = request.toString().getBytes(StandardCharsets.UTF_8);
            os.write(input, 0, input.length);
        }

        try(BufferedReader br = new BufferedReader(
                new InputStreamReader(con.getInputStream(), StandardCharsets.UTF_8))) {
            StringBuilder response = new StringBuilder();
            String responseLine = null;
            while ((responseLine = br.readLine()) != null) {
                response.append(responseLine.trim());
            }
            System.out.println(response.toString());
        }

        con.disconnect();
    }
}

<dependency>
    <groupId>org.json</groupId>
    <artifactId>json</artifactId>
    <version>20201115</version>
</dependency>