application/x-www-form-urlencoded to POJO like a boss - HandlerMethodArgumentResolver approach

SlackController.java

@RestController
@RequestMapping("/api/v1")
public class SlackController {

    private static final Logger log = LoggerFactory.getLogger(SlackController.class);

    @RequestMapping(
            value = "/slack", method = RequestMethod.POST,
            consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE, produces = MediaType.APPLICATION_JSON_VALUE
    )
    public @ResponseBody SlackSlashCommand slack(SlackSlashCommand slackSlashCommand) {
        log.info("slackSlashCommand: {}", slackSlashCommand);

        return slackSlashCommand;
    }
}

SlackSlashCommand.java

public class SlackSlashCommand {

    private String token;
    private String command;
    private String text;

    @JsonProperty("team_id")
    private String teamId;

    @JsonProperty("team_domain")
    private String teamDomain;

    @JsonProperty("channel_id")
    private String channelId;

    @JsonProperty("channel_name")
    private String channelName;

    @JsonProperty("user_id")
    private String userId;

    @JsonProperty("user_name")
    private String userName;

    @JsonProperty("response_url")
    private String responseUrl;

    public String getToken() {
        return token;
    }

    public void setToken(String token) {
        this.token = token;
    }

    public String getTeamId() {
        return teamId;
    }

    public void setTeamId(String team_id) {
        this.teamId = team_id;
    }

    public String getTeamDomain() {
        return teamDomain;
    }

    public void setTeamDomain(String teamDomain) {
        this.teamDomain = teamDomain;
    }

    public String getChannelId() {
        return channelId;
    }

    public void setChannelId(String channelId) {
        this.channelId = channelId;
    }

    public String getChannelName() {
        return channelName;
    }

    public void setChannelName(String channelName) {
        this.channelName = channelName;
    }

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getCommand() {
        return command;
    }

    public void setCommand(String command) {
        this.command = command;
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    public String getResponseUrl() {
        return responseUrl;
    }

    public void setResponseUrl(String responseUrl) {
        this.responseUrl = responseUrl;
    }

    public String toString() {
        return
            getToken() + "|" + getCommand() + "|" + getText() + "|" + getTeamId() + "|" + getTeamDomain() + "|" +
            getChannelId() + "|" + getChannelName() + "|" + getUserId() + "|" + getUserName() + "|" +
            getResponseUrl();
    }
}

SlackSlashCommandMethodArgumentResolver.java

public class SlackSlashCommandMethodArgumentResolver implements HandlerMethodArgumentResolver {

    @Override
    public boolean supportsParameter(MethodParameter methodParameter) {
        return methodParameter.getParameterType().equals(SlackSlashCommand.class);
    }

    @Override
    public Object resolveArgument(
        MethodParameter methodParameter, ModelAndViewContainer modelAndViewContainer,
        NativeWebRequest nativeWebRequest, WebDataBinderFactory webDataBinderFactory
    ) throws Exception {

        SlackSlashCommand ret = new SlackSlashCommand();

        ret.setChannelId(nativeWebRequest.getParameter("channel_id"));
        ret.setChannelName(nativeWebRequest.getParameter("channel_name"));
        ret.setCommand(nativeWebRequest.getParameter("command"));
        ret.setResponseUrl(nativeWebRequest.getParameter("response_url"));
        ret.setTeamDomain(nativeWebRequest.getParameter("team_domain"));
        ret.setTeamId(nativeWebRequest.getParameter("team_id"));
        ret.setText(nativeWebRequest.getParameter("text"));
        ret.setToken(nativeWebRequest.getParameter("token"));
        ret.setUserId(nativeWebRequest.getParameter("user_id"));
        ret.setUserName(nativeWebRequest.getParameter("user_name"));

        return ret;
    }

    private boolean isNotSet(String value) {
        return value == null;
    }
}

SlackSlashCommandMethodArgumentResolverConfig.java

@Configuration
public class SlackSlashCommandMethodArgumentResolverConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
        argumentResolvers.add(new SlackSlashCommandMethodArgumentResolver());
    }
}