public static Properties getProperties(Set<ClassLoader> classLoaders) {
        String path = System.getProperty(CommonConstants.DUBBO_PROPERTIES_KEY);
        if (StringUtils.isEmpty(path)) {
            path = System.getenv(CommonConstants.DUBBO_PROPERTIES_KEY);
            if (StringUtils.isEmpty(path)) {
                path = CommonConstants.DEFAULT_DUBBO_PROPERTIES;
            }
        }
        return ConfigUtils.loadProperties(classLoaders, path, false, true);
    }
@Test
    void testGetProperties1() throws Exception {
        try {
            System.setProperty(CommonConstants.DUBBO_PROPERTIES_KEY, "properties.load");
            Properties p = ConfigUtils.getProperties(Collections.emptySet());
            assertThat((String) p.get("a"), equalTo("12"));
            assertThat((String) p.get("b"), equalTo("34"));
            assertThat((String) p.get("c"), equalTo("56"));
        } finally {
            System.clearProperty(CommonConstants.DUBBO_PROPERTIES_KEY);
        }
    }