YAML support under PropertiesLoaderUtils

Enhancements requests

Currently https://github.com/spring-projects/spring-framework/blob/main/spring-core/src/main/java/org/springframework/core/io/support/PropertiesLoaderUtils.java#L92 provides support for parsing XML & .properties file. But it fails to parse if the properties file is defined as YAML.

Right now PropertiesLoaderUtils already checks for XML file extension & it can similarly check for YAML file extension & replace the current parsing logic with a custom implementation.

I agree that currently this can be achieved by providing a custom implementation of PropertySourceFactory as below without the need of any external library dependency

public class YamlPropertySourceFactory implements PropertySourceFactory {

    @Override
    public PropertiesPropertySource createPropertySource(String name, EncodedResource resource) {
        YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
        factory.setResources(resource.getResource());
        Properties properties = factory.getObject();
        String sourceName = (name != null) ? name : resource.getResource().getFilename();
        return new PropertiesPropertySource(sourceName, properties);
    }
}

Though considering that YAML format is getting more traction(start.spring.io started supporting YAML format last year), can an out of box support be considered for supporting YAML files?

Start with spring-core/src/main/java/org/springframework/core/io/support/PropertiesLoaderUtils.java at the XML-handling logic around line 92. Review how XML and .properties resources are parsed, then determine the expected YAML resource handling and extension checks. Done means YAML files are supported by PropertiesLoaderUtils without regressing existing XML or .properties behavior; the issue does not name a test file.