How to inject nested (inner) non-static class in micronaut?

• micronaut version: 2.2.1
• java version: 11
• OS: Windows 10

My code is as below:

import io.micronaut.context.annotation.Prototype;

import javax.inject.Inject;
import javax.inject.Singleton;

@Singleton
public class ParentObject {
    @Inject ChildClass childClass;
    String keyVar = 'FOO';

    public void parentFoo() {
        System.out.println("I am foo in parent class");
        childClass.childFoo();
    }

    @Prototype
    class ChildClass  {
        public ChildClass() {}

        public void childFoo() {
            System.out.println("I am foo in child class. keyVar is"+ ParentObject.this.keyVar);
        }
    }
}

Compile process is OK. But when the code is executing, the below errors happens:

Message: com.jcarxmate.test.ParentObject$ChildClass: method <init>()V not found
Path Taken: CoreCommand.testController --> TestController.parentObject --> ParentObject.childClass
    at picocli.CommandLine$DefaultFactory.create(CommandLine.java:5201)
    at picocli.CommandLine$Model$CommandUserObject.getInstance(CommandLine.java:11160)
    at picocli.CommandLine$Model$CommandSpec.userObject(CommandLine.java:5928)
    at picocli.CommandLine$Interpreter.clear(CommandLine.java:12323)
    at picocli.CommandLine$Interpreter.parse(CommandLine.java:12364)
    at picocli.CommandLine$Interpreter.parse(CommandLine.java:12259)
    at picocli.CommandLine.parseArgs(CommandLine.java:1458)
    at picocli.CommandLine.execute(CommandLine.java:2057)
    at io.micronaut.configuration.picocli.PicocliRunner.run(PicocliRunner.java:137)
    at io.micronaut.configuration.picocli.PicocliRunner.run(PicocliRunner.java:114)
    at com.jcarxmate.CoreCommand.main(CoreCommand.java:29)
Caused by: io.micronaut.context.exceptions.BeanInstantiationException: Error instantiating bean of type  [com.jcarxmate.test.ParentObject]

Message: com.jcarxmate.test.ParentObject$ChildClass: method <init>()V not found
Path Taken: CoreCommand.testController --> TestController.parentObject --> ParentObject.childClass
    at io.micronaut.context.DefaultBeanContext.doCreateBean(DefaultBeanContext.java:1925)
    at io.micronaut.context.DefaultBeanContext.getScopedBeanForDefinition(DefaultBeanContext.java:2424)
    at io.micronaut.context.DefaultBeanContext.getBeanForDefinition(DefaultBeanContext.java:2339)
    at io.micronaut.context.DefaultBeanContext.getBeanInternal(DefaultBeanContext.java:2311)
    at io.micronaut.context.DefaultBeanContext.getBean(DefaultBeanContext.java:1245)
    at io.micronaut.context.AbstractBeanDefinition.getBeanForField(AbstractBeanDefinition.java:1441)
    at io.micronaut.context.AbstractBeanDefinition.getBeanForField(AbstractBeanDefinition.java:1203)
    at com.jcarxmate.test.$ParentObjectDefinition.injectBean(Unknown Source)
    at com.jcarxmate.test.$ParentObjectDefinition.build(Unknown Source)
    at io.micronaut.context.DefaultBeanContext.doCreateBean(DefaultBeanContext.java:1898)
    at io.micronaut.context.DefaultBeanContext.createAndRegisterSingletonInternal(DefaultBeanContext.java:2679)
    at io.micronaut.context.DefaultBeanContext.createAndRegisterSingleton(DefaultBeanContext.java:2665)
    at io.micronaut.context.DefaultBeanContext.getBeanForDefinition(DefaultBeanContext.java:2337)
    at io.micronaut.context.DefaultBeanContext.getBeanInternal(DefaultBeanContext.java:2311)
    at io.micronaut.context.DefaultBeanContext.getBean(DefaultBeanContext.java:1245)
    at io.micronaut.context.AbstractBeanDefinition.getBeanForField(AbstractBeanDefinition.java:1441)
    at io.micronaut.context.AbstractBeanDefinition.getBeanForField(AbstractBeanDefinition.java:1203)
    at com.jcarxmate.test.$TestControllerDefinition.injectBean(Unknown Source)
    at com.jcarxmate.test.$TestControllerDefinition.build(Unknown Source)
    at io.micronaut.context.DefaultBeanContext.doCreateBean(DefaultBeanContext.java:1898)
    at io.micronaut.context.DefaultBeanContext.createAndRegisterSingletonInternal(DefaultBeanContext.java:2679)
    at io.micronaut.context.DefaultBeanContext.createAndRegisterSingleton(DefaultBeanContext.java:2665)
    at io.micronaut.context.DefaultBeanContext.getBeanForDefinition(DefaultBeanContext.java:2337)
    at io.micronaut.context.DefaultBeanContext.getBeanInternal(DefaultBeanContext.java:2311)
    at io.micronaut.context.DefaultBeanContext.getBean(DefaultBeanContext.java:1245)
    at io.micronaut.context.AbstractBeanDefinition.getBeanForField(AbstractBeanDefinition.java:1441)
    at io.micronaut.context.AbstractBeanDefinition.getBeanForField(AbstractBeanDefinition.java:1203)
    at com.jcarxmate.$CoreCommandDefinition.injectBean(Unknown Source)
    at com.jcarxmate.$CoreCommandDefinition.build(Unknown Source)
    at io.micronaut.context.DefaultBeanContext.doCreateBean(DefaultBeanContext.java:1898)
    at io.micronaut.context.DefaultBeanContext.getScopedBeanForDefinition(DefaultBeanContext.java:2424)
    at io.micronaut.context.DefaultBeanContext.getBeanForDefinition(DefaultBeanContext.java:2339)
    at io.micronaut.context.DefaultBeanContext.getBeanInternal(DefaultBeanContext.java:2311)
    at io.micronaut.context.DefaultBeanContext.findBean(DefaultBeanContext.java:1266)
    at io.micronaut.context.DefaultBeanContext.findBean(DefaultBeanContext.java:744)
    at io.micronaut.context.BeanLocator.findOrInstantiateBean(BeanLocator.java:163)
    at io.micronaut.configuration.picocli.MicronautFactory.create(MicronautFactory.java:73)
    at picocli.CommandLine$DefaultFactory.create(CommandLine.java:5197)
    ... 10 more
Caused by: java.lang.NoSuchMethodError: com.jcarxmate.test.ParentObject$ChildClass: method <init>()V not found
    at com.jcarxmate.test.$ParentObject$ChildClassDefinition.build(Unknown Source)
    at io.micronaut.context.DefaultBeanContext.doCreateBean(DefaultBeanContext.java:1898)
    ... 47 more

If I remove @Inject from the line @Inject ChildClass childClass; and add childClass = new ChildClass(); as below, it works:

public void parentFoo() {
    System.out.println("I am foo in parent class");
    childClass = new ChildClass();
    childClass.childFoo();
}

But I still hope to use @Inject if possible. However, I can not use nested static class because ChildClass has to access variables and methods in parent class.

So, any suggestion ? Thanks