Responding to binary data using AWS ALB does not work.

[damu-inka]

Describe the bug
I tried to use ALB to respond to binary data, but it only responds in JSON.

�ALB Docs

Sample

@Component
public class Handler {

    public record Response(int statusCode,
                           String statusDescription,
                           Map<String, String> headers,
                           String body,
                           boolean isBase64Encoded) {
    }

    @Bean
    public Function<String, Response> license() {
        return request -> {
            Map<String, String> responseHeaders = new HashMap<>();
            responseHeaders.put("Content-Type", MediaType.IMAGE_PNG_VALUE);
            String encodedImage = "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";

            return new Response(
                    200,
                    "200 OK",
                    responseHeaders,
                    encodedImage,
                    true
            );
        };
    }
}

I tried to send a small image by setting the isBase64Encoded option to true as shown in the documentation.

Subsequent calls to ALB returned a response in JSON form, as shown below.

{"statusCode":200,"statusDescription":"200 OK","headers":{"contentType":"image/png","Content-Type":"image/png"},"body":"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","isBase64Encoded":true}

Am I missing something?