Refactor to idiomatic Spring + Kotlin code

- Usage of Kotlin JPA compiler plugin to generate default constructors
 - Jackson builder already register Kotlin module with sensible defaults
 - One liner syntax + type inference when possible

domain/src/main/kotlin/de/rpr/mycity/domain/DoubleAttributeConverter.kt

@@ -5,15 +5,9 @@ import javax.persistence.AttributeConverter
 
 class DoubleAttributeConverter : AttributeConverter<Double, BigDecimal?> {
 
-    override fun convertToDatabaseColumn(attribute: Double?): BigDecimal? {
-        return if (attribute != null) {
-            BigDecimal(attribute)
-        } else {
-            null
-        }
-    }
+    override fun convertToDatabaseColumn(attribute: Double?) =
+            if (attribute != null) { BigDecimal(attribute) } else { null }
 
-    override fun convertToEntityAttribute(dbData: BigDecimal?): Double? {
-        return dbData?.toDouble()
-    }
+    override fun convertToEntityAttribute(dbData: BigDecimal?) =
+            dbData?.toDouble()
 }

domain/src/main/kotlin/de/rpr/mycity/domain/city/entity/CityEntity.kt

@@ -21,13 +21,6 @@ internal data class CityEntity(
         val updatedAt: LocalDateTime = LocalDateTime.now(),
         val createdAt: LocalDateTime = LocalDateTime.now()) {
 
-    // Default constructor for JPA
-    @Suppress("unused")
-    private constructor() : this(
-            name = "",
-            location = Coordinate.origin(),
-            updatedAt = LocalDateTime.MIN)
-
     fun toDto(): CityDto = CityDto(
             id = this.id!!,
             name = this.name,

pom.xml

@@ -23,7 +23,7 @@
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <java.version>1.8</java.version>
-    <kotlin.version>1.1.2-2</kotlin.version>
+    <kotlin.version>1.1.2-5</kotlin.version>
     <mockito.version>2.8.9</mockito.version>
     <assertj.version>3.8.0</assertj.version>
   </properties>
@@ -105,6 +105,7 @@
         <configuration>
           <compilerPlugins>
             <plugin>spring</plugin>
+            <plugin>jpa</plugin>
           </compilerPlugins>
           <jvmTarget>1.8</jvmTarget>
         </configuration>
@@ -130,6 +131,11 @@
             <artifactId>kotlin-maven-allopen</artifactId>
             <version>${kotlin.version}</version>
           </dependency>
+          <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-maven-noarg</artifactId>
+            <version>${kotlin.version}</version>
+          </dependency>
         </dependencies>
       </plugin>
     </plugins>

web/src/main/kotlin/de/rpr/mycity/Application.kt

@@ -1,8 +1,5 @@
 package de.rpr.mycity
 
-import com.fasterxml.jackson.databind.DeserializationFeature
-import com.fasterxml.jackson.databind.ObjectMapper
-import com.fasterxml.jackson.module.kotlin.KotlinModule
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 import org.springframework.beans.factory.InjectionPoint
@@ -18,13 +15,6 @@ class Application {
     @Scope("prototype")
     fun logger(injectionPoint: InjectionPoint): Logger = LoggerFactory.getLogger(injectionPoint.methodParameter.containingClass)
 
-    @Bean
-    fun objectMapper(): ObjectMapper {
-        val mapper = ObjectMapper().registerModule(KotlinModule())
-        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false)
-        return mapper
-    }
-
 }
 
 fun main(args: Array<String>) {