code: public Observable<AgentPoolInner> beginCreateOrUpdateAsync(String resourceGroupName, String managedClusterName, String agentPoolName, AgentPoolInner parameters) {
          return beginCreateOrUpdateWithServiceResponseAsync(resourceGroupName, managedClusterName, agentPoolName, parameters).map(new Func1<ServiceResponse<AgentPoolInner>, AgentPoolInner>() {
              @Override
              public AgentPoolInner call(ServiceResponse<AgentPoolInner> response) {
                  return response.body();
              }
          });
      }
docs: Creates or updates an agent pool.
  Creates or updates an agent pool in the specified managed cluster.
  
  @param resourceGroupName The name of the resource group.
  @param managedClusterName The name of the managed cluster resource.
  @param agentPoolName The name of the agent pool.
  @param parameters Parameters supplied to the Create or Update an agent pool operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the AgentPoolInner object