code: public VirtualMachineScaleSetExtensionInner get(String resourceGroupName, String vmScaleSetName, String vmssExtensionName, String expand) {
          return getWithServiceResponseAsync(resourceGroupName, vmScaleSetName, vmssExtensionName, expand).toBlocking().single().body();
      }
docs: The operation to get the extension.
  
  @param resourceGroupName The name of the resource group.
  @param vmScaleSetName The name of the VM scale set containing the extension.
  @param vmssExtensionName The name of the VM scale set extension.
  @param expand The expand expression to apply on the operation.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws CloudException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the VirtualMachineScaleSetExtensionInner object if successful.