hst:defaultsitemapitemhandlerids property of mount is not inherited

MountService.java contains the following:

defaultSiteMapItemHandlerIds = mount.getValueProvider().getStrings(HstNodeTypes.MOUNT_PROPERTY_DEFAULTSITEMAPITEMHANDLERIDS);
if(defaultSiteMapItemHandlerIds == null && parent != null)

{ defaultSiteMapItemHandlerIds = parent.getDefaultSiteMapItemHandlerIds(); }

This shows that it assumes the 'hst:defaultsitemapitemhandlerids' property should be inherited from the parent mount if the child mount doesn't contain it.
However, the problem is ValueProvider implementation, JCRValueProviderImpl.java, always returns an empty array if there's no property found.

Therefore, the code must be changed to check emptiness instead.