Add integer case, handle non-string types

templates/terraform/custom_flatten/default_if_empty.erb

@@ -13,8 +13,16 @@
 	# limitations under the License.
 -%>
 func flatten<%= prefix -%><%= titlelize_property(property) -%>(v interface{}, d *schema.ResourceData) interface{} {
-	if v == nil || v.(string) == "" {
+	if v == nil || isEmptyValue(reflect.ValueOf(v)) {
 		return <%= go_literal(property.default_value) -%>
 	}
+<%- if property.is_a?(Api::Type::Integer) -%>
+	// Handles the string fixed64 format
+	if strVal, ok := v.(string); ok {
+		if intVal, err := strconv.ParseInt(strVal, 10, 64); err == nil {
+			return intVal
+		} // let terraform core handle it if we can't convert the string to an int.
+	}
+<%- end %>
 	return v
 }