Unable to bind properties through application.properties in java bean using springboot

Question

My java classes looks like below

@ConfigurationProperties(prefix = "resilience.component.io")
public class IO16BrickletProperties {

    private List<IOBricklet> bricklets = new ArrayList<IOBricklet>();

    public List<IOBricklet> getBricklets() {
        return bricklets;
    }

    public void setBricklets(List<IOBricklet> bricklets) {
        this.bricklets = bricklets;
    }
}

and

public class IOBricklet extends Bricklet {

    private List<Configuration> configuration = new ArrayList<Configuration>();

    public List<Configuration> getConfiguration() {
        return configuration;
    }

    public void setConfiguration(List<Configuration> configuration) {
        this.configuration = configuration;
    }

    class Configuration {
        private char port;
        private char pin;
        private String serviceName;

        getters and setters...
        toString()...
    }
}

I want to bind values in it through application.properties. And the way i do it is

resilience.component.io.bricklets[0].uid=DBv
resilience.component.io.bricklets[0].period=100
resilience.component.io.bricklets[0].configuration[0].port=a
resilience.component.io.bricklets[0].configuration[0].pin=1
resilience.component.io.bricklets[0].configuration[0].serviceName=symbology
resilience.component.io.bricklets[0].configuration[1].port=b
resilience.component.io.bricklets[0].configuration[1].pin=1
resilience.component.io.bricklets[0].configuration[1].serviceName=elkservice

and the error i get is

2018-03-20 16:17:35.103  WARN 1344 --- [  restartedMain] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'IO16BrickletProperties': Could not bind properties to 'IO16BrickletProperties': prefix=resilience.component.io, ignoreInvalidFields=false, ignoreUnknownFields=true; nested exception is org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under 'resilience.component.io.bricklets[0].configuration' to java.util.List<netc.resilience.model.IOBricklet$Configuration>
2018-03-20 16:17:35.212  WARN 1344 --- [  restartedMain] o.s.b.f.support.DisposableBeanAdapter    : Invocation of destroy method 'close' failed on bean with name 'eurekaRegistration': org.springframework.beans.factory.BeanCreationNotAllowedException: Error creating bean with name 'org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration': Singleton bean creation not allowed while singletons of this factory are in destruction (Do not request a bean from a BeanFactory in a destroy method implementation!)

Can someone figure out why exactly am i getting this error. I referred external configuration of spring but couldn't resolve this error. What would be the correct way of configuring in properties file.

Answer 1

Need to make inner class as static. Refer spring docs.

So the update code will look like

public class IOBricklet extends Bricklet {

    private List<Configuration> configuration = new ArrayList<Configuration>();

    public List<Configuration> getConfiguration() {
        return configuration;
    }

    public void setConfiguration(List<Configuration> configuration) {
        this.configuration = configuration;
    }

    static class Configuration {
        private char port;
        private char pin;
        private String serviceName;

        getters and setters...
        toString()...
    }
}