But I define @MTOM on SEI (not on SIB but SIB do refer to SEI through 'endpointInterface') , I do not get above mentioned mtom policy definition in WSDL.
Any specific why we have this behaviour?
This annotation MUST only be used in conjunction the javax.jws.WebService, WebServiceProvider, WebServiceRef annotations. When used with the javax.jws.WebService annotation this annotation MUST only be used on the service endpoint implementation class. When used with a WebServiceRef annotation, this annotation MUST only be used when a proxy instance is created. The injected SEI proxy, and endpoint MUST honor the values of the MTOM annotation.
In short: it should be on the SIB. On the SEI it will be ignored.