Softening the new rule.

https://universaldependencies.org/u/overview/syntax.html#function-word-modifiers admits that some function words can be modified by light adverbials. The example there that involves a "det" parent of an "advmod" is negation, for which we have a separate exception earlier in this function, but perhaps other advmods may be valid, too.

Author: dan-zeman

validate.py

@@ -1731,7 +1731,7 @@ def validate_functional_leaves(id, tree):
                 testid = 'leaf-aux-cop'
                 testmessage = "'%s' not expected to have children (%s:%s:%s --> %s:%s:%s)" % (pdeprel, idparent, tree['nodes'][idparent][FORM], pdeprel, idchild, tree['nodes'][idchild][FORM], cdeprel)
                 warn(testmessage, testclass, testlevel, testid, nodeid=id, lineno=tree['linenos'][idchild])
-            if re.match(r"^(det|clf)$", pdeprel) and not re.match(r"^(goeswith|fixed|reparandum|conj|cc|punct)$", cdeprel):
+            if re.match(r"^(det|clf)$", pdeprel) and not re.match(r"^(advmod|obl|goeswith|fixed|reparandum|conj|cc|punct)$", cdeprel):
                 testid = 'leaf-det-clf'
                 testmessage = "'%s' not expected to have children (%s:%s:%s --> %s:%s:%s)" % (pdeprel, idparent, tree['nodes'][idparent][FORM], pdeprel, idchild, tree['nodes'][idchild][FORM], cdeprel)
                 warn(testmessage, testclass, testlevel, testid, nodeid=id, lineno=tree['linenos'][idchild])