With:
```
sampleObject:
type: object
additionalProperties:
$ref: '#/components/schemas/SampleData'
minProperties: 1
description: Map of Charging data policy decisions.
```
and
```
SampleData:
type: object
...
nullable: true
```
We currently generate: HashMap<String, SampleData>, which doesn't allow
null charging data entries. This MR changes this to be
`HashMap<String, swagger::Nullable<SampleData>>`, which thus will allow null data entries.
We do this by moving null-handling to the Java code - primarily `getTypeDeclaration()`.
Note, to some extent this is wrong. In this MR (and previously) we are treating
`nullable: true` as an extrinsic property (like required), whereas it should be an
intrinsic property (and thus `HashMap<String, SampleData>` is correct, but `SampleData`
absorbs the nullability.
This would be possible with this code:
```
enum ChargingData = {
Null,
Present {
...
}
}
```
Which would remove the usage of https://docs.rs/swagger/2.0.2/swagger/nullable_format/enum.Nullable.html.
I haven't resolved this - and have instead done a more targeted fix.
This, along with some other crude code, creates a scenario where we need to
unpick whether something is null. I've left that, though flagged a TODO to tidy it up at some point.
- Restore XML namespace support
- Remove non snake case rust warning for xml wrap_in methods
- Add XML rust-server tests
- Fix wrapping XML arrays when a property of another object
- Run all tests, not just those for OpenAPI 2.0
- Force wrapping for rust-server
