added handler for Nothing

Author: Wicpar

src/main/kotlin/com/papsign/ktor/openapigen/model/schema/SchemaModel.kt

@@ -42,7 +42,7 @@ sealed class SchemaModel<T>: DataModel {
     ) : SchemaModel<T>()
 
     data class SchemaModelLitteral<T>(
-        var type: DataType,
+        var type: DataType? = null,
         var format: DataFormat? = null,
         var nullable: Boolean = false,
         var minimum: T? = null,

src/main/kotlin/com/papsign/ktor/openapigen/schema/builder/provider/NothingSchemaProvider.kt

@@ -0,0 +1,33 @@
+package com.papsign.ktor.openapigen.schema.builder.provider
+
+import com.papsign.ktor.openapigen.OpenAPIGen
+import com.papsign.ktor.openapigen.OpenAPIGenModuleExtension
+import com.papsign.ktor.openapigen.getKType
+import com.papsign.ktor.openapigen.model.schema.DataType
+import com.papsign.ktor.openapigen.model.schema.SchemaModel
+import com.papsign.ktor.openapigen.modules.ModuleProvider
+import com.papsign.ktor.openapigen.schema.builder.FinalSchemaBuilder
+import com.papsign.ktor.openapigen.schema.builder.SchemaBuilder
+import kotlin.reflect.KType
+import kotlin.reflect.full.createType
+import kotlin.reflect.jvm.jvmErasure
+
+object NothingSchemaProvider: SchemaBuilderProviderModule, OpenAPIGenModuleExtension {
+
+    private object Builder: SchemaBuilder {
+        override val superType: KType = Nothing::class.createType()
+
+        override fun build(
+            type: KType,
+            builder: FinalSchemaBuilder,
+            finalize: (SchemaModel<*>) -> SchemaModel<*>
+        ): SchemaModel<*> {
+            checkType(type)
+            return finalize(SchemaModel.SchemaModelLitteral<Any?>(nullable = true))
+        }
+    }
+
+    override fun provide(apiGen: OpenAPIGen, provider: ModuleProvider<*>): List<SchemaBuilder> {
+        return listOf(Builder)
+    }
+}