public Map<String, String> getLabels(String labelType) {
		if (CollectionUtils.isEmpty(labels)) {
			return Collections.emptyMap();
		}
		Map<String, String> subLabels = labels.get(labelType);
		if (CollectionUtils.isEmpty(subLabels)) {
			return Collections.emptyMap();
		}
		return Collections.unmodifiableMap(subLabels);
	}
@Test
	public void testGetEmptyRouterContext() {
		PolarisRouterContext routerContext = new PolarisRouterContext();
		assertThat(routerContext.getLabels(RouterConstant.TRANSITIVE_LABELS).size()).isEqualTo(0);
		assertThat(routerContext.getLabels(RouterConstant.ROUTER_LABELS).size()).isEqualTo(0);
	}