`channels().post()` returns `null` when creating a shared channel (`membershipType: shared`)

Describe the bug

When creating a channel with membershipType set to ChannelMembershipType.Shared, the graphClient.teams().byTeamId(teamId).channels().post(channel) method returns null instead of a Channel object.
This works correctly for standard and private channel types, which return the expected Channel object.

Root cause analysis

According to the Microsoft Graph API documentation (Example 5 — Create a shared channel), creating a shared channel returns an HTTP 202 Accepted with a Location header pointing to a teamsAsyncOperation, whereas standard/private channels return a 201 Created with the Channel object in the response body.

The SDK's .post() method appears to only handle the 201 Created case, deserializing the response body into a Channel object. When it receives a 202 Accepted (with no Channel in the body), it returns null without providing access to the response headers or the async operation.

This is the same issue reported in the .NET SDK: microsoftgraph/msgraph-sdk-dotnet#1728

Expected behavior

One of the following:

• Preferred: The SDK should detect the 202 Accepted response, follow the Location header, poll the teamsAsyncOperation until completion, and return the resulting Channel object — providing a consistent developer experience across all channel types.

• Alternative: The SDK should return a wrapper type (e.g., ChannelPostResponse) that can represent either a Channel (for 201) or a TeamsAsyncOperation (for 202), along with the Location/Content-Location headers.

• Minimum: The documentation should clearly state that .post() returns null for shared channels, and provide a documented pattern to retrieve the channel using NativeResponseHandler (or equivalent in Java).

How to reproduce

ChannelMembershipType type = ChannelMembershipType.Shared;

Channel channel = new Channel();
channel.setOdataType("#Microsoft.Graph.channel");
channel.setMembershipType(type);
channel.setDisplayName("My Shared Channel");
channel.setDescription("Test shared channel creation");

LinkedList<ConversationMember> members = new LinkedList<>();
AadUserConversationMember conversationMember = new AadUserConversationMember();
conversationMember.setRoles(List.of("owner"));
HashMap<String, Object> additionalData = new HashMap<>();
additionalData.put("user@odata.bind",
    "https://graph.microsoft.com/v1.0/users('" + ownerId + "')");
conversationMember.setAdditionalData(additionalData);
members.add(conversationMember);
channel.setMembers(members);

// This returns null for shared channels, but works for standard/private
Channel result = graphClient.teams().byTeamId(teamId).channels().post(channel);

System.out.println(result); // null

SDK Version

6.62.0

Latest version known to work for scenario above?

6.62.0

Known Workarounds

None

Debug output

</details>


### Configuration

_No response_

### Other information

_No response_

Inizia riproducendo il caso di un canale condiviso in graphClient.teams().byTeamId(teamId).channels().post(channel) e confronta la relativa risposta 202 con le risposte 201 per i canali standard e privati. Leggi la documentazione di Microsoft Graph sulla creazione dei canali condivisi e analizza la gestione delle risposte dell’SDK; il lavoro è completato quando è stato concordato un comportamento per la risposta asincrona oppure è stata documentata chiaramente la relativa gestione se non viene apportata alcuna modifica all’API.