code: public ServiceFuture<SharedAccessAuthorizationRuleListResultInner> listKeysAsync(String resourceGroupName, String namespaceName, String authorizationRuleName, final ServiceCallback<SharedAccessAuthorizationRuleListResultInner> serviceCallback) {
          return ServiceFuture.fromResponse(listKeysWithServiceResponseAsync(resourceGroupName, namespaceName, authorizationRuleName), serviceCallback);
      }
docs: Gets the Primary and Secondary ConnectionStrings to the namespace.
  
  @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 serviceCallback the async ServiceCallback to handle successful and failed responses.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the {@link ServiceFuture} object