Retrieve fields via apply method when possible (#169)

which is the only option if the case class is defined nested within
an object.

Author: SamTheisens

src/main/scala-2/com/github/swagger/scala/converter/ErasureHelper.scala

@@ -1,16 +1,26 @@
 package com.github.swagger.scala.converter
 
+import scala.reflect.runtime.universe.TermName
+
 object ErasureHelper {
 
   def erasedOptionalPrimitives(cls: Class[_]): Map[String, Class[_]] = {
     import scala.reflect.runtime.universe
     val mirror = universe.runtimeMirror(cls.getClassLoader)
-    val sym = mirror.staticClass(cls.getName)
-    val properties = sym.selfType.members
-      .filterNot(_.isMethod)
-      .filterNot(_.isClass)
 
-    properties.flatMap { prop =>
+    val moduleSymbol = mirror.moduleSymbol(Class.forName(cls.getName))
+    val ConstructorName = "apply"
+    val companion: universe.Symbol = moduleSymbol.typeSignature.member(TermName(ConstructorName))
+    val properties = if (companion.fullName.endsWith(ConstructorName)) {
+      companion.asMethod.paramLists.flatten
+    } else {
+      val sym = mirror.staticClass(cls.getName)
+      sym.selfType.members
+        .filterNot(_.isMethod)
+        .filterNot(_.isClass)
+    }
+
+    properties.flatMap { prop: universe.Symbol =>
       val maybeClass: Option[Class[_]] = prop.typeSignature.typeArgs.headOption.flatMap { signature =>
         if (signature.typeSymbol.isClass) {
           Option(mirror.runtimeClass(signature.typeSymbol.asClass))

src/test/scala/com/github/swagger/scala/converter/ModelPropertyParserTest.scala

@@ -3,6 +3,7 @@ package com.github.swagger.scala.converter
 import io.swagger.v3.core.converter._
 import io.swagger.v3.core.util.Json
 import io.swagger.v3.oas.models.media._
+import models.NestingObject.NestedModelWOptionInt
 import models._
 import org.scalatest.OptionValues
 import org.scalatest.flatspec.AnyFlatSpec
@@ -117,6 +118,41 @@ class ModelPropertyParserTest extends AnyFlatSpec with Matchers with OptionValue
     nullSafeList(model.value.getRequired) shouldBe empty
   }
 
+  it should "process Model with nested Scala Option Int" in {
+    val converter = ModelConverters.getInstance()
+    val schemas = converter.readAll(classOf[NestedModelWOptionInt]).asScala.toMap
+    val model = schemas.get("NestedModelWOptionInt")
+    model should be(defined)
+    model.value.getProperties should not be (null)
+    val optInt = model.value.getProperties().get("optInt")
+    optInt should not be (null)
+    if (RuntimeUtil.isScala3()) {
+      optInt shouldBe a[ObjectSchema]
+    } else {
+      optInt shouldBe a[IntegerSchema]
+      optInt.asInstanceOf[IntegerSchema].getFormat shouldEqual "int32"
+    }
+    nullSafeList(model.value.getRequired) shouldBe empty
+  }
+
+  it should "process Model with nested Scala Option Int with Schema Override" in {
+    val converter = ModelConverters.getInstance()
+    val schemas = converter.readAll(classOf[ModelWOptionIntSchemaOverride]).asScala.toMap
+    val model = schemas.get("ModelWOptionIntSchemaOverride")
+    model should be(defined)
+    model.value.getProperties should not be (null)
+    val optInt = model.value.getProperties().get("optInt")
+    optInt should not be (null)
+    if (RuntimeUtil.isScala3()) {
+      optInt shouldBe a[ObjectSchema]
+    } else {
+      optInt shouldBe a[IntegerSchema]
+      optInt.asInstanceOf[IntegerSchema].getFormat shouldEqual "int32"
+    }
+    optInt.getDescription shouldBe "This is an optional int"
+    nullSafeList(model.value.getRequired) shouldBe empty
+  }
+
   it should "process Model with Scala Option Int with Schema Override" in {
     val converter = ModelConverters.getInstance()
     val schemas = converter.readAll(classOf[ModelWOptionIntSchemaOverride]).asScala.toMap

src/test/scala/models/ModelWOptionInt.scala

@@ -4,6 +4,11 @@ import io.swagger.v3.oas.annotations.media.Schema
 
 case class ModelWOptionInt(optInt: Option[Int])
 
+object NestingObject {
+  case class NestedModelWOptionInt(optInt: Option[Int])
+  case class NestedModelWOptionIntSchemaOverride(@Schema(description = "This is an optional int") optInt: Option[Int])
+}
+
 case class ModelWOptionIntSchemaOverride(@Schema(description = "This is an optional int") optInt: Option[Int])
 
 case class ModelWOptionIntSchemaOverrideForRequired(@Schema(required = true) optInt: Option[Int])