Spring Feign Client JSON parse error: Illegal character

Question

I am sending a GET request to an API. This API requires some sort of compression, gzip in my case. Here is the implementation:

Client

@FeignClient("client",
        url = "someUrl",
        configuration = [ClientConfig::class])
@RequestMapping(consumes = [MediaType.APPLICATION_JSON_VALUE], produces = [MediaType.APPLICATION_JSON_VALUE])
interface Client {
    
    @GetMapping("/data")
    fun data(): CustomResponse
}

ClientConfig

class ClientConfig {

    @Bean
    fun gzipFeignRequestInterceptor(): RequestInterceptor {
        return GzipFeignRequestInterceptor()
    }

    class GzipFeignRequestInterceptor : RequestInterceptor {
        override fun apply(template: RequestTemplate) {
            template.header("Accept-Encoding",  "gzip")
        }
    }
}

When i try to call the data() method I get the following error:

feign.codec.DecodeException: Error while extracting response for type [class java.lang.Object] and content type [application/json]; nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\r, \n, \t) is allowed between tokens; nested exception is com.fasterxml.jackson.core.JsonParseException: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\r, \n, \t) is allowed between tokens

I understand the error message but I don't know how to fix it. Is it possible to filter the response before it is further processed?

The request itself shouldn't be a problem, when I try to make the same request in the browser it works fine.

Answer 1

Solved the problem by adding the following properties in my application.yml

feign.compression.response.enabled=true
feign.compression.response.useGzipDecoder=true