assertTrue(result.contains("at ")); // Stack trace indicator
        }

        @Test
        @DisplayName("Should handle root cause without message")
        void testToStringWithRootCauseNoMessage() {
            Exception rootCause = new NullPointerException();
            TransportException exception = new TransportException(rootCause);

            String result = exception.toString();

Shinsuke Sugaya <******@****.***> 1755149504 +0900