code: public ServiceFuture<SharedAccessAuthorizationRuleResourceInner> getAuthorizationRuleAsync(String resourceGroupName, String namespaceName, String authorizationRuleName, final ServiceCallback<SharedAccessAuthorizationRuleResourceInner> serviceCallback) {
          return ServiceFuture.fromResponse(getAuthorizationRuleWithServiceResponseAsync(resourceGroupName, namespaceName, authorizationRuleName), serviceCallback);
      }
docs: Gets an authorization rule for a namespace by name.
  
  @param resourceGroupName The name of the resource group.
  @param namespaceName The namespace name
  @param authorizationRuleName Authorization rule name.
  @param serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object