[Question] "Caused by: java.lang.IllegalStateException: Only KClass supported as classifier, got T"

[yamatakau08]

Could you please teach me how to fix the the exception on the following code?
Caused by: java.lang.IllegalStateException: Only KClass supported as classifier, got T

My code is the following.

@Serializable
data class Params<T>(val params: T)        

val rparams7 = listOf(mapOf("settings" to listOf(mapOf("value" to "2", "target" to "color"))))
val params7  = Params(rparams7)
Log.d(TAG,"params7: ${Json.encodeToString(params7)}") // → params7: {"params":[{"settings":[{"value":"2","target":"color"}]}]}

This Serialization and Json.encodeToString works with no problem.

Next, I prepare the xpost func then pass the rparams7 as the raw data to that function which execute the same process
Serialization and Json.encodeToString likely the above code.

val rparams7 = listOf(mapOf("settings" to listOf(mapOf("value" to "2", "target" to "color"))))
xpost(rparams7)

fun <T> xpost(params: List<T>) {
    val x = Params(params)
    Log.d(TAG,"xpost x : $x") // -> xpost x : Params(params=[{settings=[{value=2, target=color}]}])
    val y = Json.encodeToString(x)　 // Caused by: java.lang.IllegalStateException: Only KClass supported as classifier, got T
    Log.d(TAG,"xpost Json.encodeToString : $y")
    // myhttp.post(url, y)
}

But xpost Json.encodeToString has the Exception.
Caused by: java.lang.IllegalStateException: Only KClass supported as classifier, got T

Could you advice me how to fix this exception.
I just want to pass the Json.encodeToString value from xpost function to the onward function.

Environment
Android Studio Bumblebee 2021.1.1
build.gradle (Project: My_Application) classpath "org.jetbrains.kotlin:kotlin-serialization:1.6.10"
build.gradle (Module: My_Application.app) implementation 'org.jetbrains.kotlinx:kotlinx-serialization-json:1.3.2'

[qwwdfsad]

This is because T is erased by JVM and we have no actual type parameters information. Unfortunately, we cannot do much except for better error message here.

As a workaround, you can make your function inline and T -- reified

[yamatakau08]

Thank you for your advice.

, you can make your function inline and T -- reified

As you mentioned, other community also taught me to add
inline fun <reified T>.
this makes work successfully.

 //fun <T> xpost(params: List<T>) {
 inline fun <reified T> xpost(params: List<T>) {
     val x = Params(params)
     Log.d("HOGE","xpost x : $x") // -> in case rparams7, xpost x : Params(params=[{settings=[{value=2, target=color}]}])
     val y = Json.encodeToString(x)
     Log.d("HOGE","xpost Json.encodeToString : $y")
 }