In a deployment with two servers connected with a load balancer and functioning as a single Identity Provider, you must set the following properties in the AMConfig.properties file:
com.sun.identity.liberty.interaction.lbWspRedirectHandler com.sun.identity.liberty.interaction.trustedWspRedirectHandlers
The com.sun.identity.liberty.interaction.interactionConfigClass is the only class currently supported. Thus, by default, the interaction configuration class bundled with Federation Liberty is used to access the interaction configuration parameters.