code: public VirtualMachineExtensionInner createOrUpdate(String resourceGroupName, String vmName, String vmExtensionName, VirtualMachineExtensionInner extensionParameters) {
          return createOrUpdateWithServiceResponseAsync(resourceGroupName, vmName, vmExtensionName, extensionParameters).toBlocking().last().body();
      }
docs: The operation to create or update the extension.
  
  @param resourceGroupName The name of the resource group.
  @param vmName The name of the virtual machine where the extension should be created or updated.
  @param vmExtensionName The name of the virtual machine extension.
  @param extensionParameters Parameters supplied to the Create Virtual Machine Extension 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 VirtualMachineExtensionInner object if successful.