SpringMVC过滤器修改Long类型字段为String后，前端解析JSON失败是什么原因？

public class LongTypeFilter extends OncePerRequestFilter {
    private final ObjectMapper objectMapper = new ObjectMapper();

    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException {
        ContentCachingResponseWrapper responseWrapper = new ContentCachingResponseWrapper(response);
        filterChain.doFilter(request, responseWrapper);
        byte[] responseBody = responseWrapper.getContentAsByteArray();
        String charset = response.getCharacterEncoding();

        if (contentType != null && contentType.startsWith(MediaType.APPLICATION_JSON_VALUE)) {
            JsonNode rootNode = objectMapper.readTree(new String(responseBody, charset));
            if (rootNode.has("code") && rootNode.has("msg") && rootNode.has("result")) {
                JsonNode resultNode = rootNode.get("result");
                checkAndConvertLongToString(resultNode);
            }
            String modifiedResponse = rootNode.toString();
            responseWrapper.setContentType(MediaType.APPLICATION_JSON_VALUE + ";charset=" + charset);
            byte[] modifiedBytes = modifiedResponse.getBytes(charset);
            responseWrapper.setContentLength(modifiedBytes.length);
            responseWrapper.getWriter().write(modifiedResponse);
            responseWrapper.copyBodyToResponse();
        } else {
            responseWrapper.copyBodyToResponse();
        }
    }

    private void checkAndConvertLongToString(JsonNode node) {
        // ... (递归转换Long到String的逻辑，与原代码相同) ...
    }
}

@Bean
public Jackson2ObjectMapperBuilderCustomizer addLongConverter() {
    return builder -> {
        builder.serializerByType(Long.class, new JsonSerializer<Long>() {
            @Override
            public void serialize(Long value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
                gen.writeString(String.valueOf(value));
            }
        });
    };
}