SpringBoot 2 the elements were left unbound

i have a file application.yml with my Spring Boot application which is not willing to run.

According to logs the reason of The elements [simulator.geo.b12,simulator.geo.b13,simulator.geo.b21,simulator.geo.c6,simulator.geo.host] were left unbound. This property however is set in application.yml and compiler is even returning it's value.

I'll really appreciate if someone could lend me a hand with that issue.

simulator:
    geo:
        host: http://localhost:8080/
        b12: http://localhost:8080/geo/b12
        b13: http://localhost:8080/geo/b13
        b21: http://localhost:8080/geo/b21
        c6: http://localhost:8080/geo/c6

and java class

@Getter
@Configuration
@ConfigurationProperties(prefix = "simulator",ignoreUnknownFields = false)
public class VendorSimulatorProperties {

    @Value("${simulator.geo.host:http://localhost:8080/}")
    private String initUrl;

    @Value("${simulator.geo.b12}")
    private String geoB12Url;

    @Value("${simulator.geo.b13}")
    private String geoB13Url;

    @Value("${simulator.geo.b21}")
    private String geoB21Url;

    @Value("${simulator.geo.c6}")
    private String geoC6Url;
}

when i start to run application, i got the error msg :

**************************
APPLICATION FAILED TO START
***************************

Description:

Binding to target [Bindable@1c140c7c type = com.mathartsys.dlc.thirdparty.vendor.config.VendorSimulatorProperties$$EnhancerBySpringCGLIB$$eb0a550b, value = 'provided', annotations = array<Annotation>[@org.springframework.boot.context.properties.ConfigurationProperties(prefix=simulator, value=simulator, ignoreUnknownFields=false, ignoreInvalidFields=false)]] failed:

    Property: simulator.geo.b12
    Value: http://localhost:8080/geo/b12
    Origin: class path resource [config/application-dev.yml]:204:14
    Reason: The elements [simulator.geo.b12,simulator.geo.b13,simulator.geo.b21,simulator.geo.c6,simulator.geo.host] were left unbound.
    Property: simulator.geo.b13
    Value: http://localhost:8080/geo/b13
    Origin: class path resource [config/application-dev.yml]:205:14
    Reason: The elements [simulator.geo.b12,simulator.geo.b13,simulator.geo.b21,simulator.geo.c6,simulator.geo.host] were left unbound.
    Property: simulator.geo.b21
    Value: http://localhost:8080/geo/b21
    Origin: class path resource [config/application-dev.yml]:206:14
    Reason: The elements [simulator.geo.b12,simulator.geo.b13,simulator.geo.b21,simulator.geo.c6,simulator.geo.host] were left unbound.
    Property: simulator.geo.c6
    Value: http://localhost:8080/geo/c6
    Origin: class path resource [config/application-dev.yml]:207:13
    Reason: The elements [simulator.geo.b12,simulator.geo.b13,simulator.geo.b21,simulator.geo.c6,simulator.geo.host] were left unbound.
    Property: simulator.geo.host
    Value: http://localhost:8080/
    Origin: class path resource [config/application-dev.yml]:203:15
    Reason: The elements [simulator.geo.b12,simulator.geo.b13,simulator.geo.b21,simulator.geo.c6,simulator.geo.host] were left unbound.

this problem had confuse me long time, i hope someone can give me some advice; i used springboot 2.0 thanks

The problem is that you are using the @ConfigurationProperties in a wrong way. You use either @ConfigurationProperties or @Value but not both.

The solution either fix your class to be usable for @ConfigurationProperties or remove the @ConfigurationProperties annotation.

@Getter
@Setter
@Component
@ConfigurationProperties(prefix = "simulator.geo",ignoreUnknownFields = false)
public class VendorSimulatorProperties {

    private String host = "http://localhost:8080/";
    private String b12;
    private String b13;
    private String b21;
    private String c6;

}

You need to fix the prefix it should be simulator.geo and your properties should be named after the keys in your file. You will also require setter next to the getter. However this will also need to change the rest of your configuration, to use the newly generated getters.

For you it is probably easier to remove @ConfigurationProperties as you weren't really using them in the first place.