Yes, I was able to apply content filtering settings to a numbered group policy.
*I never said it was documented. 😉 I just have a strong need for that, and it worked when I tried it. I only tried it because when I did a GET on the group policies they DID include content filtering. Now they don't.
This is what I got 2 weeks ago when I did the GET on /groupPolicies/100
{"groupPolicyId":100,
"name":"Trust",
"scheduling":
{"enabled":false,
"monday":
{"active":true,
"from":"00:00",
"to":"24:00"},
"tuesday":
{"active":true,
"from":"00:00",
"to":"24:00"},
"wednesday":
{"active":true,
"from":"00:00",
"to":"24:00"},
"thursday":
{"active":true,
"from":"00:00",
"to":"24:00"},
"friday":
{"active":true,
"from":"00:00",
"to":"24:00"},
"saturday":
{"active":true,
"from":"00:00",
"to":"24:00"},
"sunday":
{"active":true,
"from":"00:00",
"to":"24:00"}},
"bandwidth":
{"settings":"network default",
"bandwidthLimits":
{"limitUp":null,
"limitDown":null}},
"firewallAndTrafficShaping":
{"settings":"network default",
"trafficShapingRules":[],
"l3FirewallRules":[],
"l7FirewallRules":[]},
"contentFiltering":
{"allowedUrlPatterns":
{"settings":"override",
"patterns":["statflow.com",
"google.com"'
"yellowpages.ca",
"411.ca"]},
"blockedUrlPatterns":
{"settings":"override",
"patterns":[".ca",
".com",
".pw"]},
"blockedUrlCategories":
{"settings":"override",
"categories":["meraki:contentFiltering/category/11",
"meraki:contentFiltering/category/64",
"meraki:contentFiltering/category/56",
"meraki:contentFiltering/category/62",
"meraki:contentFiltering/category/25"]}}}