Terminal pivot operations return incorrect `T` schema, should be Any? instead

result of pivot is always new set of columns created based on data in columns. Current return type is a guaranteed runtime exception:

Operations like public fun <T> Pivot<T>.count(): DataRow<T> = delegate { count() } should become

public fun <T> Pivot<T>.count(): DataRow<*> = delegate { count() }

students.json

import org.jetbrains.kotlinx.dataframe.DataFrame
import org.jetbrains.kotlinx.dataframe.annotations.*
import org.jetbrains.kotlinx.dataframe.api.*
import org.jetbrains.kotlinx.dataframe.io.*

@DataSchema
data class Students(
    val age: Int,
    val name: Name,
    val scores: List<Scores>
) {
    @DataSchema
    data class Name(
        val firstName: String,
        val lastName: String?
    )

    @DataSchema
    data class Scores(
        val subject: String,
        @ColumnName("value")
        val `value`: Int
    )
}

fun main() {
    val students = DataFrame.readJson("/home/nikita/IdeaProjects/dataframe-examples/students.json")
        .cast<Students>()

    students.explode { scores }.pivot { scores.subject }.count().schema().print()
}

=>

math: Int
biology: Int
music: Int
nothing: Int
russian: Int
art: Int

There's some connection to original data if "with" is used, but even so it's still misleading. As a side note,

students.explode { scores }.pivot { scores.subject }.with { it }.schema().print()

math: *
    name:
        firstName: String
        lastName: String
    age: Int
    scores:
        subject: String
        value: Int

biology: *
    name:
        firstName: String
        lastName: String
    age: Int
    scores:
        subject: String
        value: Int

music:
    name:
        firstName: String
        lastName: String
    age: Int
    scores:
        subject: String
        value: Int

nothing:
    name:
        firstName: String
        lastName: String?
    age: Int
    scores:
        subject: String
        value: Int

russian:
    name:
        firstName: String
        lastName: String
    age: Int
    scores:
        subject: String
        value: Int

art:
    name:
        firstName: String
        lastName: String
    age: Int
    scores:
        subject: String
        value: Int

Start at the terminal Pivot operations, including Pivot.count(), and reproduce the schema output with the Students example and students.json. Check the generated return types against the runtime pivot columns, then verify that terminal pivot results expose an unknown schema type such as DataRow<*> rather than a misleading T.