TokenHelper - Could not find token mapped to token name struts.token

TokenHelper - Could not find token mapped to token name struts.token

If I add the "execAndWait" interceptor, it gives me the above error.
"TokenHelper - Could not find token mapped to token name struts.token"
<action name="flightsearch" method="getFlightResult"
class="com.test.FlightSearchAction">
<interceptor-ref name="execAndWait">
<param name="delay">500</param>
<param name="delaySleepInterval">500</param>
</interceptor-ref>
<!-- <interceptor-ref name="token">
<param name="excludeMethods">getFlightResult</param>
</interceptor-ref> -->
<result name="wait" type="tiles">flightwait</result>
<result name="success" type="tiles">flightsearchresult</result>
</action>
<interceptors>
<interceptor-stack name="tokenCheck">
<interceptor-ref name="token" />
<interceptor-ref name="defaultStack" />
<interceptor-ref name="basicStackHibernate" />
</interceptor-stack>
<interceptor-stack name="loggingRequired">
<interceptor-ref name="defaultStack" />
<interceptor-ref name="basicStackHibernate" />
</interceptor-stack>
</interceptors>
As I have read, some says this is an warning, and we can avoid it by
changing the TokenHelper class. If so how to do that?
Thanks.