code: public Observable<DeploymentValidateResultInner> validateAsync(String resourceGroupName, String deploymentName, DeploymentProperties properties) {
          return validateWithServiceResponseAsync(resourceGroupName, deploymentName, properties).map(new Func1<ServiceResponse<DeploymentValidateResultInner>, DeploymentValidateResultInner>() {
              @Override
              public DeploymentValidateResultInner call(ServiceResponse<DeploymentValidateResultInner> response) {
                  return response.body();
              }
          });
      }
docs: Validates whether the specified template is syntactically correct and will be accepted by Azure Resource Manager..
  
  @param resourceGroupName The name of the resource group the template will be deployed to. The name is case insensitive.
  @param deploymentName The name of the deployment.
  @param properties The deployment properties.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the DeploymentValidateResultInner object