SessionNotCreatedException while adding the firefox driver in selenium

can you please mention where to include this code.

In main method or where ???

I copied your code and wrote in main method and it is showing "Syntax error on tokens, Label expected instead"

THIS IS THE CODE WRITTEN ::: ERROR IS WRITTEN DOWN THE CODE

imports-----

public class MobilemenuClass {

public static void main(String[] args) {
    
    {
    
        "capabilities": ,
        "alwaysMatch": ,
        "moz:firefoxOptions": {
        "binary": "/usr/local/firefox/bin/firefox",
        "args": ["-headless", "-profile", "/path/to/my/profile"],
        "prefs": {
        "dom.ipc.processCount": 9,
        "javascript.options.showInConsole": true
        },
        "log": {"level": "trace"}
        }
        }
        }
        }
        if(driverParameter == null || driverParameter.equalsIgnoreCase(FIREFOX))
        {
        DesiredCapabilities capabilities = DesiredCapabilities.firefox();
        FirefoxOptions options = new FirefoxOptions();
        options.setHeadless(headless);
        capabilities.merge(options);
        } 
        System.setProperty("webdriver.gecko.driver", "D:\\Selenium Stuff\\Selenium jars\\geckodriver-v0.21.0-win64\\geckodriver.exe");


    driver.get("https://www.javatpoint.com/selenium-webdriver-running-test-on-firefox-browser-gecko-driver");
    System.out.println(driver.getTitle());
    driver.quit();
}

}

THIS WAS THE ERROR BEFORE ADDING YOUR capabilites CODE:::::

Exception in thread "main" org.openqa.selenium.SessionNotCreatedException: Could not start a new session. Response code 400. Message: Unrecognised option moz:debuggerAddress Build info: version: '4.0.0-beta-4', revision: '29f46d02dd' System info: host: 'DESKTOP-HNR5CK4', ip: '192.168.1.4', os.name: 'Windows 10', os.arch: 'amd64', os.version: '10.0', java.version: '15.0.2' Driver info: org.openqa.selenium.firefox.FirefoxDriver Command: [null, newSession {capabilities=[Capabilities {acceptInsecureCerts: true, browserName: firefox, moz:debuggerAddress: true, moz:firefoxOptions: {}}], desiredCapabilities=Capabilities {acceptInsecureCerts: true, browserName: firefox, moz:debuggerAddress: true, moz:firefoxOptions: {}}}] at org.openqa.selenium.remote.ProtocolHandshake.createSession(ProtocolHandshake.java:126) at org.openqa.selenium.remote.ProtocolHandshake.createSession(ProtocolHandshake.java:84) at org.openqa.selenium.remote.ProtocolHandshake.createSession(ProtocolHandshake.java:62) at org.openqa.selenium.remote.HttpCommandExecutor.execute(HttpCommandExecutor.java:156) at org.openqa.selenium.remote.service.DriverCommandExecutor.invokeExecute(DriverCommandExecutor.java:162) at org.openqa.selenium.remote.service.DriverCommandExecutor.execute(DriverCommandExecutor.java:137) at org.openqa.selenium.remote.RemoteWebDriver.execute(RemoteWebDriver.java:612) at org.openqa.selenium.remote.RemoteWebDriver.startSession(RemoteWebDriver.java:244) at org.openqa.selenium.remote.RemoteWebDriver.(RemoteWebDriver.java:165) at org.openqa.selenium.firefox.FirefoxDriver.(FirefoxDriver.java:205) at org.openqa.selenium.firefox.FirefoxDriver.(FirefoxDriver.java:193) at org.openqa.selenium.firefox.FirefoxDriver.(FirefoxDriver.java:171) at Ecom_package.MobilemenuClass.main(MobilemenuClass.java:16)

Please help me ...