static HttpResponse ofJson(MediaType contentType, Object content) {
        return ofJson(HttpStatus.OK, contentType, content);
    }
Creates a new HTTP response with the specified {@link MediaType} and {@code content} that is
converted into JSON using the default {@link ObjectMapper}.

@throws IllegalArgumentException if the specified {@link MediaType} is not a JSON compatible type; or
                                 if failed to encode the {@code content} into JSON.
@see JacksonObjectMapperProvider
core/src/main/java/com/linecorp/armeria/common/HttpResponse.java