title: Finding the azure account key with Blob Service Client fails(azure python sdk)
body: <p>I am using
  Name: azure-mgmt-storage
  Version: 16.0.0
  Summary: Microsoft Azure Storage Management Client Library for Python
  Home-page: <a href="https://github.com/Azure/azure-sdk-for-python" rel="nofollow noreferrer">https://github.com/Azure/azure-sdk-for-python</a></p>
  <p>for generating a report to find the storage container size.
  The snippet of my code that I am using is as below</p>
  <pre class="lang-py prettyprint-override"><code>from azure.mgmt.storage import StorageManagementClient
  
  subscription_client = Subscription(tenant=tenant_id, client_id=client_id, secret=client_secret)
  service_principals = subscription_client.credentials
  subscription_id = subscription_client.find_subscription_id()
  storage_client = StorageManagementClient(credential=service_principals, subscription_id=subscription_id)
  storage_account_list = storage_client.storage_accounts.list()
  for storage_account in storage_account_list:
      blob_service_client = BlobServiceClient(account_url=storage_account.primary_endpoints.blob,credential=service_principals)
                      account_info = blob_service_client.get_service_properties()
      keys = blob_service_client.credential.keys()
  </code></pre>
  <p>When I evaluate expression <code>blob_service_client.credential</code>, value is</p>
  <pre class="lang-py prettyprint-override"><code>&lt;azure.identity._credentials.client_secret.ClientSecretCredential object at 0x05747E98&gt;
  </code></pre>
  <ol>
  <li><p><code>blob_service_client.api_version</code> evaluates to <code>2020-02-10</code>.</p>
  </li>
  <li><p>And <code>blob_service_client.credential.account_key</code> or <code>blob_service_client.credential.account_key()</code> evaluates to <code>{AttributeError}'ClientSecretCredential' object has no attribute 'account_key'</code></p>
  </li>
  <li><p>or even when I try <code>blob_service_client.credential.keys()</code> I get <code>{AttributeError}'ClientSecretCredential' object has no attribute 'keys'</code> error</p>
  </li>
  </ol>
  <p>Any Azure expert can help me out here? Also connnection strings are another way to approach this problem where I can use:</p>
  <pre class="lang-py prettyprint-override"><code>BlobServiceClient.from_connection_string(connection_string)
  </code></pre>
  <p>for which I am also required to generate the connection_string dynamically, which I am unable to.</p>