public Document process(Document input) throws TransformerException {
        Document doc = Xml.copyDocument(input);
        Document document = buildProperties(doc);
        applyProperties(document.getDocumentElement());
        return document;
    }
Handles getting properties from services.xml and replacing references to properties with their real values

@author hmusum
config-application-package/src/main/java/com/yahoo/config/application/PropertiesProcessor.java