[BUG] `planInformation()` of `ReservationOrderResponse` always returns `null`

[Tomasz-Kluczkowski]

Describe the bug
A clear and concise description of what the bug is.

planInformation() method of ReservationOrderResponse always returns null.
All other reservation order data is present on all returned items from result of calling manager.reservationOrders().list() and iterating/viewing it in debug mode.

Exception or Stack Trace
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N/A

To Reproduce
Steps to reproduce the behavior:

Run the code snippet, all other reservation order data is present but the billing plan information.

Code Snippet
Add the code snippet that causes the issue.

public class GetCosts {
    public static void main(String[] args) {
        AzureProfile profile = new AzureProfile(AzureEnvironment.AZURE);
        TokenCredential credential = new DefaultAzureCredentialBuilder()
                .authorityHost(profile.getEnvironment().getActiveDirectoryEndpoint())
                .build();
        ReservationsManager manager = ReservationsManager
                .authenticate(credential, profile);

        manager.reservationOrders().list().forEach(
                reservationOrder -> System.out.println(reservationOrder.planInformation())
                );
    }
}

Expected behavior
A clear and concise description of what you expected to happen.

call to planInformation of ReservationOrderResponse contains plan information as described here: https://learn.microsoft.com/en-us/java/api/com.azure.resourcemanager.reservations.models.reservationorderbillingplaninformation?view=azure-java-preview

Screenshots
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Output of the above snippet:

17:12:22.359 [main] INFO com.azure.identity.ChainedTokenCredential -- Azure Identity => Attempted credential EnvironmentCredential is unavailable.
17:12:22.361 [main] INFO com.azure.identity.ChainedTokenCredential -- Azure Identity => Attempted credential WorkloadIdentityCredential is unavailable.
17:12:22.924 [ForkJoinPool.commonPool-worker-1] INFO com.azure.identity.ChainedTokenCredential -- Azure Identity => Attempted credential ManagedIdentityCredential is unavailable.
17:12:22.930 [ForkJoinPool.commonPool-worker-1] INFO com.azure.identity.ChainedTokenCredential -- Azure Identity => Attempted credential SharedTokenCacheCredential is unavailable.
17:12:23.074 [ForkJoinPool.commonPool-worker-1] INFO com.azure.identity.ChainedTokenCredential -- Azure Identity => Attempted credential IntelliJCredential is unavailable.
17:12:24.063 [ForkJoinPool.commonPool-worker-1] INFO com.azure.identity.AzureCliCredential -- Azure Identity => getToken() result for scopes [https://management.core.windows.net//.default]: SUCCESS
17:12:24.063 [ForkJoinPool.commonPool-worker-1] INFO com.azure.identity.ChainedTokenCredential -- Azure Identity => Attempted credential AzureCliCredential returns a token
17:12:24.065 [ForkJoinPool.commonPool-worker-1] INFO com.azure.core.implementation.AccessTokenCache -- {"az.sdk.message":"Acquired a new access token."}
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Setup (please complete the following information):

• OS: [e.g. iOS] Mac OS Sonoma 14.1 (23B74)
• IDE: [e.g. IntelliJ] IntelliJ
• Library/Libraries: [e.g. com.azure:azure-core:1.16.0 (groupId:artifactId:version)] azure-resourcemanager-reservations, 1.0.0-beta.2
• Java version: [e.g. 8] openjdk 21.0.1 2023-10-17
• App Server/Environment: [e.g. Tomcat, WildFly, Azure Function, Apache Spark, Databricks, IDE plugin or anything special]
• Frameworks: [e.g. Spring Boot, Micronaut, Quarkus, etc] Spring Boo

If you suspect a dependency version mismatch (e.g. you see NoClassDefFoundError, NoSuchMethodError or similar), please check out Troubleshoot dependency version conflict article first. If it doesn't provide solution for the problem, please provide:

• verbose dependency tree (mvn dependency:tree -Dverbose)
• exception message, full stack trace, and any available logs

Additional context
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Information Checklist
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• Bug Description Added
• Repro Steps Added
• Setup information Added

[joshfree]

Thanks for filing this github issue, @Tomasz-Kluczkowski. @weidongxu-microsoft could you please follow up?

[Tomasz-Kluczkowski]

I now have additional information after experimenting today with the reservation orders api.

Looks like some fields in reservations api are not filled in the api it uses and what I had to do was:

Get reservation orders
Iterate over their reservation order ids (which by the way do not work as input to reservation orders getWithResponse method (the method expects only the uuid section of the returned id, I had to string split it) which I then had to use to get reservation order with plan information specifying expand parameter as schedule (this is not documented anywhere, I had to figure it out from azure's REST api examples), on top of that the signature of getWithResponse expects required argument context, which in my case was absolutely not necessary and I would think it would be better if it was optional as I had to fake it with nonsense data just to make getWithResponse work.

After I have done all that I got a response for reservation order including its plan information.

I believe this could be made much more pleasant and in a way which avoids calling 3 apis and making many calls in the last one to get the detail of each individual reservation order plan information. Could make it less performance taxing to azure's dbs this way :).

I will post some code to visualise this tomorrow when back at work.

Writing this on a train so may have misnamed method or two - will fix tomorrow.

Better documentation could be a great first improvement step please.