Extensions in subobjects of OpenAPI no longer work

[ezoerner]

This is closely related to #2104, which states that extensions in the OpenAPI object no longer work.
This was fixed for extensions at the top level, but extension in sub-parts of OpenAPI are also no longer working. One of these sub-objects is the Info object which can also have extensions. I believe there are extensions in other sub-parts that are probably also not working.

I've verified that the extensions of Info are not working in v1.6.8, 1.16.15, and 1.7.0.

[bnasslahsen]

@ezoerner,

I have added a fix for it.
Let me know if the fix works for you with the latest snapshot.

[bmr-exerp]

Hi, this change appears to have caused a regression: see #1655 .

I've encountered a similar problem to the linked github issue, in that I'm trying to serialise a JsonNullable<T>. I configure the ObjectMapperProvider to use new JsonNullableModule(), but that module is ignored because the OpenAPIService uses new ObjectMapper.

As a consequence, when I try to create POJO examples programmatically, e.g.

	Foo example = new Foo(JsonNullable.of("bar"), JsonNullable.of(null));
	.addExamples("foo", new Example()
			.description("fooBar")
			.summary("fooBarBaz")
			.value(example1))

Then the example is serialised as:

{
	"bar": {
		"present": true
	}
	"baz": {
		"present": true
	}
}

instead of

{
	"bar": "bar",
	"baz": null
}

I want to use 1.8.0 because of its support for OpenAPI spec version 3.1.0, so this is a major problem for me.