@ExtendWith({TestReporter.class})
private TestClass{
   String result;
   
   @Test
   void testA(){
     //some action here
     result = some result;
   }
}

public class TestReporter implements BeforeAllCallback, BeforeTestExecutionCallback, AfterAllCallback,
       TestWatcher {
    private static ExtentHtmlReporter htmlReporter;
    private static ExtentReports extent;
    private static ExtentTest test;
    @Override
    public void beforeAll(ExtensionContext context) throws Exception {
       //set up extent report
    }
   @Override
   public void testSuccessful(ExtensionContext context) {
     //not possible, but desired
     test.pass(context.getElement.get("result"), MediaEntityBuilder.createScreenCaptureFromPath("test"+count+".png").build());
   }
}

@ExtendWith(TestReporter.class)
public class TestClass {
	String result;
	@Test
	void testA() {
		result = "some result";
	}
}
class TestReporter implements AfterEachCallback {
	@Override
	public void afterEach(final ExtensionContext context) throws Exception {
		Object testInstance = context.getRequiredTestInstance();
		Field resultField = testInstance.getClass().getDeclaredField("result");
		String resultValue = (String) resultField.get(testInstance);
		System.out.println("Value of result: " + resultValue);
	}
}