SpringBoot Filter out null fields for structured logging

My use case is adding global service.id field along side with builtin service.name via StructuredLoggingJsonMembersCustomizer, Application.current() will be available after some point, unexpected "service.id":null is appended before that point.

public class ServiceIdStructuredLoggingJsonMembersCustomizer implements StructuredLoggingJsonMembersCustomizer<String> {

    @Override
    public void customize(JsonWriter.Members<String> members) {
        members.add("service.id", () -> Application.current().map(Application::getInstanceId).orElse(null));
    }
}

Comment From: wilkinsona

You can use whenNotNull to indicate that you want a member to only be included when it has a non-null value:

public class ServiceIdStructuredLoggingJsonMembersCustomizer implements StructuredLoggingJsonMembersCustomizer<String> {

    @Override
    public void customize(JsonWriter.Members<String> members) {
        members.add("service.id", () -> Application.current().map(Application::getInstanceId).orElse(null))
            .whenNotNull();
    }

}