Add support for empty model properties that are valid in OpenAPI

(cherry picked from commit e3421dd)

Author: vyobukhov

src/openApi/v3/parser/escapeName.ts

@@ -1,5 +1,5 @@
-export function escapeName(value: string): string {
-    if (value) {
+export const escapeName = (value: string): string => {
+    if (value || value === '') {
         const validName = /^[a-zA-Z_$][\w$]+$/g.test(value);
         if (!validName) {
             return `'${value}'`;