From 4942d6dc1416d5a6eb6f4199f42e567bc38b719e Mon Sep 17 00:00:00 2001
From: Dave Garred <dave.garred@gmail.com>
Date: Thu, 23 Nov 2023 10:21:39 -0800
Subject: [PATCH] Support empty properties

Empty properties are allowed under the OpenAPI spec and resolve to
'any'. This fixes a breakage when encountering these types.

This example taken from the [Discord API spec](https://github.com/discord/discord-api-spec/blob/main/specs/openapi.json) breaks on the `pull_request` property:

https://raw.githubusercontent.com/davegarred/openapi-generator/test_empty_property/openapi.json
---
 .../java/org/openapitools/codegen/OpenAPINormalizer.java   | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java
index 378cee272b10..ffa903d7cd7b 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java
@@ -908,10 +908,15 @@ private Schema processNormalize31Spec(Schema schema, Set<Schema> visitedSchemas)
             return schema;
         }
 
-        if (schema == null || schema.getTypes() == null) {
+        if (schema == null) {
             return null;
         }
 
+        if (schema.getTypes() == null || schema.getTypes().isEmpty()) {
+            schema.setNullable(true);
+            return schema;
+        }
+
         // process null
         if (schema.getTypes().contains("null")) {
             schema.setNullable(true);