@Override
    protected Map<String, Object> getContent() {
        Map<String,Object> thisContent = super.getContent();
        Map<String,Object> backingContent = backingProfile.getContent();
        if (thisContent.isEmpty()) return backingContent; // Shortcut
        if (backingContent.isEmpty()) return thisContent; // Shortcut
        Map<String, Object> content = new HashMap<>(backingContent);
        content.putAll(thisContent);
        return content;
    }
Returns all the content from this:
All the values in this, and all values in the backing where an overriding value is not set in this
container-search/src/main/java/com/yahoo/search/query/profile/BackedOverridableQueryProfile.java