Prioritize explicitly specified format

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

@@ -1,6 +1,7 @@
 package com.github.swagger.scala.converter
 
 import scala.reflect.runtime.universe
+import scala.util.Try
 
 object ErasureHelper {
 
@@ -10,14 +11,13 @@ object ErasureHelper {
     val moduleSymbol = mirror.moduleSymbol(Class.forName(cls.getName))
     val ConstructorName = "apply"
     val companion: universe.Symbol = moduleSymbol.typeSignature.member(universe.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)
-    }
+    val properties =
+      Try(companion.asTerm.alternatives.head.asMethod.paramLists.flatten).getOrElse {
+        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 =>

src/main/scala/com/github/swagger/scala/converter/SwaggerScalaModelConverter.scala

@@ -2,8 +2,7 @@ package com.github.swagger.scala.converter
 
 import java.lang.annotation.Annotation
 import java.lang.reflect.ParameterizedType
-import java.util.Iterator
-import com.fasterxml.jackson.databind.JavaType
+import com.fasterxml.jackson.databind.{JavaType, ObjectMapper}
 import com.fasterxml.jackson.databind.`type`.ReferenceType
 import com.fasterxml.jackson.module.scala.introspect.{BeanIntrospector, PropertyDescriptor}
 import com.fasterxml.jackson.module.scala.{DefaultScalaModule, JsonScalaEnumeration}
@@ -22,11 +21,10 @@ import scala.util.control.NonFatal
 class AnnotatedTypeForOption extends AnnotatedType
 
 object SwaggerScalaModelConverter {
-  val objectMapper = Json.mapper().registerModule(DefaultScalaModule)
+  val objectMapper: ObjectMapper = Json.mapper().registerModule(DefaultScalaModule)
 }
 
 class SwaggerScalaModelConverter extends ModelResolver(SwaggerScalaModelConverter.objectMapper) {
-  SwaggerScalaModelConverter
 
   private val logger = LoggerFactory.getLogger(classOf[SwaggerScalaModelConverter])
   private val VoidClass = classOf[Void]
@@ -40,7 +38,7 @@ class SwaggerScalaModelConverter extends ModelResolver(SwaggerScalaModelConverte
   private val ProductClass = classOf[Product]
   private val AnyClass = classOf[Any]
 
-  override def resolve(`type`: AnnotatedType, context: ModelConverterContext, chain: Iterator[ModelConverter]): Schema[_] = {
+  override def resolve(`type`: AnnotatedType, context: ModelConverterContext, chain: util.Iterator[ModelConverter]): Schema[_] = {
     val javaType = _mapper.constructType(`type`.getType)
     val cls = javaType.getRawClass
 
@@ -80,13 +78,12 @@ class SwaggerScalaModelConverter extends ModelResolver(SwaggerScalaModelConverte
         val introspector = BeanIntrospector(cls)
         val erasedProperties = ErasureHelper.erasedOptionalPrimitives(cls)
         introspector.properties.foreach { property =>
-          val propertyClass = getPropertyClass(property)
+          val (propertyClass, propertyAnnotations) = getPropertyClassAndAnnotations(property)
           val isOptional = isOption(propertyClass)
-          val propertyAnnotations = getPropertyAnnotations(property)
           val schemaOverrideClass = propertyAnnotations.collectFirst {
             case s: SchemaAnnotation if s.implementation() != VoidClass => s.implementation()
           }
-          if (schemaOverrideClass.isEmpty) {
+          if (schemaOverrideClass.isEmpty && schema.getProperties != null) {
             erasedProperties.get(property.name).foreach { erasedType =>
               val primitiveType = PrimitiveType.fromType(erasedType)
               if (primitiveType != null && isOptional) {
@@ -137,7 +134,9 @@ class SwaggerScalaModelConverter extends ModelResolver(SwaggerScalaModelConverte
     val propAsString = objectMapper.writeValueAsString(itemSchema)
     val correctedSchema = objectMapper.readValue(propAsString, primitiveProperty.getClass)
     correctedSchema.setType(primitiveProperty.getType)
-    correctedSchema.setFormat(primitiveProperty.getFormat)
+    if (itemSchema.getFormat == null) {
+      correctedSchema.setFormat(primitiveProperty.getFormat)
+    }
     correctedSchema
   }
 
@@ -261,54 +260,30 @@ class SwaggerScalaModelConverter extends ModelResolver(SwaggerScalaModelConverte
     }
   }
 
-  private def getPropertyClass(property: PropertyDescriptor): Class[_] = {
+  private def getPropertyClassAndAnnotations(property: PropertyDescriptor): (Class[_], Seq[Annotation]) = {
     property.param match {
-      case Some(constructorParameter) => {
+      case Some(constructorParameter) =>
         val types = constructorParameter.constructor.getParameterTypes
-        if (constructorParameter.index > types.size) {
-          AnyClass
+        val annotations = constructorParameter.constructor.getParameterAnnotations
+        val index = constructorParameter.index
+        if (index > types.size) {
+          (AnyClass, Seq.empty)
         } else {
-          types(constructorParameter.index)
+          val onlyType = types(index)
+          val onlyAnnotations = if (index > annotations.size) { Seq.empty[Annotation] } else { annotations(index).toIndexedSeq }
+          (onlyType, onlyAnnotations)
         }
-      }
-      case _ => property.field match {
-        case Some(field) => field.getType
-        case _ => property.setter match {
-          case Some(setter) if setter.getParameterCount == 1 => {
-            setter.getParameterTypes()(0)
-          }
-          case _ => property.beanSetter match {
-            case Some(setter) if setter.getParameterCount == 1 => {
-              setter.getParameterTypes()(0)
-            }
-            case _ => AnyClass
-          }
-        }
-      }
-    }
-  }
-
-  private def getPropertyAnnotations(property: PropertyDescriptor): Seq[Annotation] = {
-    property.param match {
-      case Some(constructorParameter) => {
-        val types = constructorParameter.constructor.getParameterAnnotations
-        if (constructorParameter.index > types.size) {
-          Seq.empty
-        } else {
-          types(constructorParameter.index).toSeq
-        }
-      }
       case _ => property.field match {
-        case Some(field) => field.getAnnotations.toSeq
+        case Some(field) => (field.getType, field.getAnnotations.toSeq)
         case _ => property.setter match {
           case Some(setter) if setter.getParameterCount == 1 => {
-            setter.getAnnotations().toSeq
+            (setter.getParameterTypes()(0), setter.getAnnotations.toSeq)
           }
           case _ => property.beanSetter match {
             case Some(setter) if setter.getParameterCount == 1 => {
-              setter.getAnnotations().toSeq
+              (setter.getParameterTypes()(0), setter.getAnnotations.toSeq)
             }
-            case _ => Seq.empty
+            case _ => (AnyClass, Seq.empty)
           }
         }
       }

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

@@ -3,7 +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.NestingObject.{NestedModelWOptionInt, NoProperties}
 import models._
 import org.scalatest.OptionValues
 import org.scalatest.flatspec.AnyFlatSpec
@@ -38,6 +38,13 @@ class ModelPropertyParserTest extends AnyFlatSpec with Matchers with OptionValue
     stringWithDataType should not be (null)
     stringWithDataType shouldBe a [StringSchema]
     nullSafeList(stringWithDataType.getRequired) shouldBe empty
+
+    val ipAddress = model.value.getProperties().get("ipAddress")
+    ipAddress should not be (null)
+    ipAddress shouldBe a[StringSchema]
+    ipAddress.getDescription shouldBe "An IP address"
+    ipAddress.getFormat shouldBe "IPv4 or IPv6"
+    nullSafeList(ipAddress.getRequired) shouldBe empty
   }
 
   it should "process Option[Model] as Model" in {
@@ -135,6 +142,16 @@ class ModelPropertyParserTest extends AnyFlatSpec with Matchers with OptionValue
     nullSafeList(model.value.getRequired) shouldBe empty
   }
 
+  it should "process Model without any properties" in {
+    val converter = ModelConverters.getInstance()
+    val schemas = converter.readAll(classOf[NoProperties]).asScala.toMap
+    val model = schemas.get("NoProperties")
+    model should be(defined)
+    model.value.getProperties should be (null)
+    model.get shouldBe a[Schema[_]]
+    model.get.getDescription shouldBe "An empty case class"
+  }
+
   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

src/test/scala/models/ModelWOptionInt.scala

@@ -6,6 +6,17 @@ case class ModelWOptionInt(optInt: Option[Int])
 
 object NestingObject {
   case class NestedModelWOptionInt(optInt: Option[Int])
+
+  @Schema(description = "An empty case class")
+  case class NoProperties()
+
+  object NestedModelWOptionInt {
+
+    def apply(nonOptional: Int): NestedModelWOptionInt = {
+      NestedModelWOptionInt(Some(nonOptional))
+    }
+  }
+
   case class NestedModelWOptionIntSchemaOverride(@Schema(description = "This is an optional int") optInt: Option[Int])
 }
 

src/test/scala/models/ModelWOptionString.scala

@@ -3,10 +3,11 @@ package models
 import io.swagger.v3.oas.annotations.Parameter
 import io.swagger.v3.oas.annotations.media.Schema
 
-case class ModelWOptionString (
-           stringOpt: Option[String],
-           stringWithDataTypeOpt: Option[String])
-
+case class ModelWOptionString (stringOpt: Option[String],
+                               stringWithDataTypeOpt: Option[String],
+                               @Schema(description = "An IP address", format = "IPv4 or IPv6")
+                               ipAddress: Option[String]
+                              )
 
 case class ModelWOptionModel (modelOpt: Option[ModelWOptionString])