xfire异常：For input string: ""

soap请求包中，包含：
<param3 href="#id0"/>
<multiRef id="id0" soapenc:root="0" soapenv:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" 
xsi:type="xsd:long" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/">
3000
</multiRef>
java代码中，
@WebService(name = "**", targetNamespace = "***")
@SOAPBinding(use = SOAPBinding.Use.LITERAL, parameterStyle = SOAPBinding.ParameterStyle.BARE)
抛出类型转换异常:
java.lang.NumberFormatException: For input string: ""
   at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
   at java.lang.Long.parseLong(Long.java:424)
   at java.lang.Long.parseLong(Long.java:461)
   at org.codehaus.xfire.aegis.AbstractMessageReader.getValueAsLong(AbstractMessageReader.java:78)
可能原因：xfire不识别  href这种赋值方式
如何才能让xfire识别 href 这种参数赋值格式？