public static String getSystemProperty(String key) {
        String value = System.getenv(key);
        if (StringUtils.isEmpty(value)) {
            value = System.getProperty(key);
        }
        return value;
    }
@Test
    void testGetSystemProperty() throws Exception {
        try {
            System.setProperty("dubbo", "system-only");
            assertThat(ConfigUtils.getSystemProperty("dubbo"), equalTo("system-only"));
        } finally {
            System.clearProperty("dubbo");
        }
    }