null-property property from application.yml is mapped to empty String

[theotherp]

With Spring Boot 1.5.2.RELEASE I have a String property that is mapped to an application.yml by @ConfigurationProperties. The value in the yml file is null (or ~). But the values are initialized with "" (empty String). According to YAML specification it does allow null values.

The "culprit" is org.springframework.beans.factory.config.YamlProcessor#buildFlattenedMap which executes result.put(key, (value != null ? value : ""))

I've extended the file and configured it to be used and this seems to work fine. But I have to take over a lot of final and private code which makes it a bit brittle. I think Spring should support null values, explicitly remark that their converted to "" or make a change in behavior a bit more comfortable.

Code excerpts:

test:
    setting: ~

@ConfigurationProperties("test")
public class Test {

    String setting;

    public void setSetting(String setting) {
        this.setting = setting; //Will set "setting" to "" instead of null
    }
}

Thanks for your time.

demo.zip

[wilkinsona]

@theotherp The code that you have identified is part of Spring Framework rather than Spring Boot. If you'd like to pursue this change, please open a Spring Framework JIRA ticket.

[theotherp]

Oops, sorry. I should've seen that looking at the package name but because it's a problem that affects externalized configuration I thought it would fit here.

Nevertheless I think this should be mentioned in Spring Boot's documentation.

[candrews]

Reported at https://jira.spring.io/browse/SPR-15425