Adds an extension element to the W3CEndpointReference instance's wsa:EndpointReference element.

Parameters:

element

The extension element to be added to the W3CEndpointReference

Returns:  A W3CEndpointReferenceBuilder instance with the extension element added to the W3CEndpointReference instance.

Exceptions:

java.lang.IllegalArgumentException

if element is null.

Since:  JAX-WS 2.2