hibernate - Kotlin with JPA: default constructor hell -

as jpa requires, @entity classes should have default (non-arg) constructor instantiate objects when retrieving them database.

in kotlin, properties convenient declare within primary constructor, in following example:

class person(val name: string, val age: int) { /* ... */ } 

but when non-arg constructor declared secondary 1 requires values primary constructor passed, valid values needed them, here:

@entity class person(val name: string, val age: int) {     private constructor(): this("", 0) } 

in case when properties have more complex type string , int , they're non-nullable, looks totally bad provide values them, when there's code in primary constructor , init blocks , when parameters actively used -- when they're reassigned through reflection of code going executed again.

moreover, val-properties cannot reassigned after constructor executes, immutability lost.

so question is: how can kotlin code adapted work jpa without code duplication, choosing "magic" initial values , loss of immutability?

p.s. true hibernate aside of jpa can construct objects no default constructor?

as of kotlin 1.0.6, kotlin-noarg compiler plugin generates synthetic default construtors classes have been annotated selected annotations.

if use gradle, applying kotlin-jpa plugin enough generate default constructors classes annotated @entity:

buildscript {     dependencies {         classpath "org.jetbrains.kotlin:kotlin-noarg:$kotlin_version"     } }  apply plugin: "kotlin-jpa" 

for maven:

<plugin>     <artifactid>kotlin-maven-plugin</artifactid>     <groupid>org.jetbrains.kotlin</groupid>     <version>${kotlin.version}</version>      <configuration>         <compilerplugins>             <plugin>jpa</plugin>         </compilerplugins>     </configuration>      <dependencies>         <dependency>             <groupid>org.jetbrains.kotlin</groupid>             <artifactid>kotlin-maven-noarg</artifactid>             <version>${kotlin.version}</version>         </dependency>     </dependencies> </plugin>