core/org.jetbrains.kotlinx.dataframe.impl.codeGen/ExtensionsCodeGeneratorImpl/generateExtensionProperties

generateExtensionProperties

protected fun generateExtensionProperties(marker: IsolatedMarker, withNullable: Boolean = true): Code

nullable properties can be needed when DECLARED schema is referenced with nullability:

@DataSchema
data class Schema(val i: Int)

@DataSchema
data class A(
 val prop: Schema?
)

When converted listOf<A>().toDataFrame(maxDepth=2) actual schema is

prop:
    i: Int?

So this sudden i: Int? must be somehow handled. However, REPL code generator will not create such a situation. Nullable properties are not needed then