case 1:
betaSourceConstraints = new SingleBetaConstraints( list.get(0),
buildContext.getKnowledgeBase().getConfiguration() );
break;
case 2:
betaSourceConstraints = new DoubleBetaConstraints( list.toArray( new BetaNodeFieldConstraint[2] ),
buildContext.getKnowledgeBase().getConfiguration() );
break;
case 3:
betaSourceConstraints = new TripleBetaConstraints( list.toArray( new BetaNodeFieldConstraint[2] ),
buildContext.getKnowledgeBase().getConfiguration() );