POJO request params workaround

controller.kt

class Controller {
  
    @GetMapping
    fun list(
            @AuthenticationPrincipal authorizedUser: AuthorizedUser,
            uriBuilder: UriComponentsBuilder,
            @Validated params: ListConversationParams): Single<PaginatedResources<..>> {
       
      val selfLink = selfLink(uriBuilder, on(javaClass).list(authorizedUser, uriBuilder, prams))
      
      ...
    }

  
}

HateoasHelper.kt

object HateoasHelper {
  
    fun link(builder: UriComponentsBuilder, invocationInfo: Any): Link {

        val queryParams = getQueryParams(invocationInfo)

        val uri = MvcUriComponentsBuilder
                .relativeTo(builder)
                .withMethodCall(invocationInfo)
                .queryParams(queryParams)
                .build()

        return Link(uri)
    }

    /**
     * Extracts query params suitable for `MvcUriComponentsBuilder`:
     *
     * It looks for method argument of type `QueryParams` which it inspects
     * and reads all public members and their values
     */
    private fun getQueryParams(invocationInfo: Any): MultiValueMap<String, String> {

        val arguments = when (invocationInfo) {
            is MethodInvocationInfo -> invocationInfo.argumentValues
            else -> emptyArray()
        }

        val ordinaryMap = arguments
                .mapNotNull { it as? QueryParams }
                .flatMap { getValues(it) }
                .toMap()
                .mapValues { listOf(it.value.toString()) }

        return LinkedMultiValueMap(ordinaryMap)
    }

    private fun getValues(params: QueryParams): List<Pair<String, Any>> = params
            .javaClass
            .kotlin
            .declaredMemberProperties
            .filter { it.visibility == KVisibility.PUBLIC }
            .map { it.name to it.get(params) }
            .mapNotNull { pair -> pair.second?.let { pair.first to it } }
  
 
}

links.kt

//the marker interface - it was added for different reason, but works well for the workaround as well :)
interface QueryParam

//query params POJO
data class ListConversationParams(

        val tag: String?,

        @get:PositiveNumber
        val assigned_to: String?,

        @get:ValidCommaSeparatedList
        val mailbox: String?
) : QueryParam