fix(python): use proper struct default value

The old {} default value caused problems in the python template when
it was looking the specific type having a .dict() field on default
values.

pkg/gen/filters/filterpy/py_default.go

@@ -41,7 +41,8 @@ func ToDefaultString(schema *model.Schema, prefix string) (string, error) {
 			if s == nil {
 				return "xxx", fmt.Errorf("ToDefaultString struct %s not found", schema.Type)
 			}
-			text = "{}"
+			ident := common.CamelTitleCase(s.Name)
+			text = fmt.Sprintf("%s%s()", prefix, ident)
 		case model.TypeInterface:
 			i := schema.Module.LookupInterface(schema.Type)
 			if i == nil {

pkg/gen/filters/filterpy/py_default_test.go

@@ -56,7 +56,7 @@ func TestDefaultSymbolsFromIdl(t *testing.T) {
 		rt string
 	}{
 		{"test", "Test2", "propEnum", "Enum1.DEFAULT"},
-		{"test", "Test2", "propStruct", "{}"},
+		{"test", "Test2", "propStruct", "Struct1()"},
 		{"test", "Test2", "propInterface", "None"},
 		{"test", "Test2", "propEnumArray", "[]"},
 		{"test", "Test2", "propStructArray", "[]"},