question: private Collection < Expression > createUniqueTriggerExpressions ( final ConversationStates state , final Collection < String > triggerStrings , final ExpressionMatcher matcher , final ChatCondition condition , final String reply , final ChatAction action ) { Collection < Expression > triggerExpressions = new ArrayList < Expression > ( ) ; for ( final String triggerString : triggerStrings ) { final Expression triggerExpression = ConversationParser . createTriggerExpression ( triggerString , matcher ) ; final Transition existing = get ( state , triggerExpression , condition ) ; if ( existing != null ) { final String existingReply = existing . getReply ( ) ; final PostTransitionAction existingAction = existing . getAction ( ) ; if ( ( existingReply != null ) && ( reply != null ) && ! existingReply . contains ( reply ) ) { existing . setReply ( existingReply + " " + reply ) ; } else { existing . setReply ( reply ) ; } if ( ( ( action == null ) && ( existingAction == null ) ) || ( ( action != null ) && action . equals ( existingAction ) ) ) { return null ; } else { logger . warn ( speakerNPC . getName ( ) + ": Adding ambiguous state transition: " + existing + " existingAction='" + existingAction + "' newAction='" + action + "'" ) ; } } triggerExpressions . add ( triggerExpression ) ; } return triggerExpressions ; }
target:  Create a collection of trigger expressions from trigger strings while checking for duplicate transitions.