修改网关返回异常信息时的response 请求头

在网关检查验证码或client信息产生异常时，在返回的response请求头中添加Content-type

pig-gateway/src/main/java/com/pig4cloud/pig/gateway/filter/ValidateCodeGatewayFilter.java

@@ -34,6 +34,7 @@ import org.springframework.cloud.gateway.filter.GatewayFilter;
 import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
 import org.springframework.data.redis.core.RedisTemplate;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
 import org.springframework.stereotype.Component;
@@ -81,6 +82,7 @@ public class ValidateCodeGatewayFilter extends AbstractGatewayFilterFactory {
 			} catch (Exception e) {
 				ServerHttpResponse response = exchange.getResponse();
 				response.setStatusCode(HttpStatus.PRECONDITION_REQUIRED);
+                response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
 				try {
 					return response.writeWith(Mono.just(response.bufferFactory()
 						.wrap(objectMapper.writeValueAsBytes(