code: public ServiceFuture<ResourceListKeysInner> regenerateKeysAsync(String resourceGroupName, String namespaceName, String authorizationRuleName, String policyKey, final ServiceCallback<ResourceListKeysInner> serviceCallback) {
          return ServiceFuture.fromResponse(regenerateKeysWithServiceResponseAsync(resourceGroupName, namespaceName, authorizationRuleName, policyKey), serviceCallback);
      }
docs: Regenerates the Primary/Secondary Keys to the Namespace Authorization Rule.
  
  @param resourceGroupName The name of the resource group.
  @param namespaceName The namespace name.
  @param authorizationRuleName The connection string of the namespace for the specified authorizationRule.
  @param policyKey Name of the key that has to be regenerated for the Namespace/Notification Hub Authorization Rule. The value can be Primary Key/Secondary Key.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object