check for IsComputed when validating a schema obj

GH-14784 allowed nested structures to be validate, rather than relying
on the raw value. However this still returns the same validation error
if the structures contain a computed value, since Get will return the
raw string in that case.

This simply skips the validation in the IsComputed case, since there's
nothing that can be checked.

helper/schema/schema.go

@@ -1374,7 +1374,7 @@ func (m schemaMap) validateObject(
 	schema map[string]*Schema,
 	c *terraform.ResourceConfig) ([]string, []error) {
 	raw, _ := c.Get(k)
-	if _, ok := raw.(map[string]interface{}); !ok {
+	if _, ok := raw.(map[string]interface{}); !ok && !c.IsComputed(k) {
 		return nil, []error{fmt.Errorf(
 			"%s: expected object, got %s",
 			k, reflect.ValueOf(raw).Kind())}

helper/schema/schema_test.go

@@ -3974,6 +3974,35 @@ func TestSchemaMap_Validate(t *testing.T) {
 			Err: false,
 		},
 
+		"Good sub-resource, computed value": {
+			Schema: map[string]*Schema{
+				"ingress": &Schema{
+					Type:     TypeList,
+					Optional: true,
+					Elem: &Resource{
+						Schema: map[string]*Schema{
+							"from": &Schema{
+								Type:     TypeInt,
+								Optional: true,
+							},
+						},
+					},
+				},
+			},
+
+			Config: map[string]interface{}{
+				"ingress": []interface{}{
+					`${map("from", var.port)}`,
+				},
+			},
+
+			Vars: map[string]string{
+				"var.port": config.UnknownVariableValue,
+			},
+
+			Err: false,
+		},
+
 		"Invalid/unknown field": {
 			Schema: map[string]*Schema{
 				"availability_zone": &Schema{