What is the @DisplayNameGeneration annotation in JUnit 6?

import org.junit.jupiter.api.DisplayNameGeneration;
import org.junit.jupiter.api.DisplayNameGenerator;

// Converts method names to sentences:
// - Removes underscores
// - Removes trailing parentheses
// "it_should_return_empty_when_null()" -> "it should return empty when null"
@DisplayNameGeneration(DisplayNameGenerator.ReplaceUnderscores.class)
class OrderServiceDisplayTest {

    @Test
    void new_order_has_pending_status() { ... }
    // Displayed as: "new order has pending status"

    @Test
    void order_with_invalid_quantity_throws_exception() { ... }
    // Displayed as: "order with invalid quantity throws exception"
}

// IndicativeSentences: generates "ClassName, method name"
@DisplayNameGeneration(DisplayNameGenerator.IndicativeSentences.class)
class PaymentTest {
    @Test
    void processValidPayment() { ... }
    // Displayed as: "PaymentTest, processValidPayment()"
}

// Custom generator:
public class CamelCaseToSentenceGenerator implements DisplayNameGenerator {
    @Override
    public String generateDisplayNameForClass(Class<?> cls) {
        return splitCamelCase(cls.getSimpleName());
    }
    @Override
    public String generateDisplayNameForNestedClass(Class<?> cls) {
        return splitCamelCase(cls.getSimpleName());
    }
    @Override
    public String generateDisplayNameForMethod(Class<?> cls, Method method) {
        return splitCamelCase(method.getName());
    }
    private String splitCamelCase(String name) {
        return name.replaceAll("([A-Z])", " $1").trim().toLowerCase();
    }
}

// Set globally in junit-platform.properties:
// junit.jupiter.displayname.generator.default=
//   org.junit.jupiter.api.DisplayNameGenerator$ReplaceUnderscores