Fail fast when base path and an endpoint mapping are set to '/'

Throw an exception if actuator is running on the main server port and
the base path and an individual mapping are set to '/'.

See gh-45251

Signed-off-by: yongjunhong <dev.yongjunh@gmail.com>

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-actuator/src/test/java/smoketest/actuator/ManagementEndpointConflictSmokeTest.java

@@ -0,0 +1,27 @@
+package smoketest.actuator;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.boot.SpringApplication;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+/**
+ * Verifies that an exception is thrown when management and server endpoint paths
+ * conflict.
+ *
+ * @author Yongjun Hong
+ */
+class ManagementEndpointConflictSmokeTest {
+
+	@Test
+	void shouldThrowExceptionWhenManagementAndServerPathsConflict() {
+		assertThatThrownBy(() -> {
+			SpringApplication.run(SampleActuatorApplication.class, "--management.endpoints.web.base-path=/",
+					"--management.endpoints.web.path-mapping.health=/");
+		}).isInstanceOf(BeanCreationException.class)
+			.hasMessageContaining("Management endpoints and endpoint path are both mapped to '/'");
+	}
+
+}