code: public Observable<HubVirtualNetworkConnectionInner> getAsync(String resourceGroupName, String virtualHubName, String connectionName) {
          return getWithServiceResponseAsync(resourceGroupName, virtualHubName, connectionName).map(new Func1<ServiceResponse<HubVirtualNetworkConnectionInner>, HubVirtualNetworkConnectionInner>() {
              @Override
              public HubVirtualNetworkConnectionInner call(ServiceResponse<HubVirtualNetworkConnectionInner> response) {
                  return response.body();
              }
          });
      }
docs: Retrieves the details of a HubVirtualNetworkConnection.
  
  @param resourceGroupName The resource group name of the VirtualHub.
  @param virtualHubName The name of the VirtualHub.
  @param connectionName The name of the vpn connection.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the HubVirtualNetworkConnectionInner object