DecodeException on Map<String, List<String>> result

[khauser]

Hi,

I do have this REST-Resource in my project:

    @GetMapping(ASYNC_MESSAGE + MULTI + KEY_VAR)
    Map<String, List<String>> getNextMessages(@PathVariable(KEY) String[] keys, @RequestParam(LIMIT) Integer limit);

A call on the resources results in an exception:

Sch-Pool4","level":"ERROR","level_value":40000,"stack_trace":"feign.codec.DecodeException: null
\tat feign.InvocationContext.decode(InvocationContext.java:118)
\tat feign.InvocationContext.proceed(InvocationContext.java:88)
\tat feign.ResponseHandler.handleResponse(ResponseHandler.java:63)
\tat feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:114)
\tat feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:70)
\tat feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:99)
\tat jdk.proxy3/jdk.proxy3.$Proxy227.getNextMessages(Unknown Source)

If I execute the call manually I get:

{
    "TS_start_queue": []
}

What could be the reason for this? There are no specialites in my environment with spring boot 3.2.7 and spring cloud 2023.0.2.

[kdavisk6]

Without more information, and possible a minimal reproducible example, I'm not sure where to begin.

The exception you are seeing is part of the general RuntimeException handling and appears to indicate a NullPointerException during decoding. Given that Spring is involved here, I recommend first looking into your Decoder configuration and try working backwards into Feign.

If you find that there's an issue in Feign itself, please provide that feedback in this issue.