Handling `null` values in the trait merge mechanism

The specification does not explicitly define how `null` values in traits or target objects should be interpreted.

While it references the JSON Merge Patch algorithm (which assigns special meaning to `null` values in merge patches), it also states that "a property on a trait MUST NOT override the same property on the target object." This creates ambiguity regarding how to reconcile the special meaning of `null` values in a patch with this overriding restriction.

I have tested several examples and examined the output from the `@asyncapi/parser`. The results differ depending on whether it is a top-level property (directly under the Operation/Operation Trait Object) or a nested property (e.g., within a binding under the Operation/Operation Trait Object), which is confusing.

Could you please clarify how `null` values should be interpreted in the trait merge mechanism—and whether they should be interpreted at all?

```javascript
// operations.myOperation['x-test'] === null
// operations.myOperation.bindings.kafka['x-test'] === null
const spec = {
asyncapi: '3.0.0',
info: {
title: 'Object null properties, no traits merge',
version: '1.0',
},
channels: {
myChannel: {}
},
operations: {
myOperation: {
action: 'send',
channel: {
$ref: '#/channels/myChannel'
},
'x-test': null,
bindings: {
kafka: {
'x-test': null
}
}
}
}
}
```

```javascript
// operations.myOperation['x-test'] === null
// operations.myOperation.bindings.kafka['x-test'] === undefined
const spec = {
asyncapi: '3.0.0',
info: {
title: 'Object null properties, trigger traits merge',
version: '1.0',
},
channels: {
myChannel: {}
},
operations: {
myOperation: {
action: 'send',
channel: {
$ref: '#/channels/myChannel'
},
'x-test': null,
bindings: {
kafka: {
'x-test': null
}
},
traits: [
{}
]
}
}
}
```

```javascript
// operations.myOperation['x-test'] === null
// operations.myOperation.bindings.kafka['x-test'] === undefined
const spec = {
asyncapi: '3.0.0',
info: {
title: 'Trait null properties',
version: '1.0',
},
channels: {
myChannel: {}
},
operations: {
myOperation: {
action: 'send',
channel: {
$ref: '#/channels/myChannel'
},
traits: [
{
'x-test': null,
bindings: {
kafka: {
'x-test': null
}
},
}
]
}
}
}
```

Read the JSON Merge Patch reference and the trait merge wording, then reproduce the three examples with @asyncapi/parser. Compare how null behaves in top-level and nested properties. Done means the specification explicitly defines whether null is interpreted and gives consistent behavior for both locations.

Written by the indexing model from the issue text.