private Converter buildConverter() {
			return new Converter<String, List<FlowRule>>() {
				ObjectMapper objectMapper = new ObjectMapper();

				@Override
				public List<FlowRule> convert(String source) {
					try {
						return objectMapper.readValue(source,
								new TypeReference<List<FlowRule>>() {
								});
					}
					catch (IOException e) {
						// ignore
					}
					return null;
				}
			};
		}
@author <a href="mailto:fangjian0423@gmail.com">Jim</a>
spring-cloud-alibaba-starters/spring-cloud-alibaba-sentinel-datasource/src/test/java/com/alibaba/cloud/sentinel/datasource/FileRefreshableDataSourceFactoryBeanTests.java