added BlueprintCallable flag to Participant ID getter

Source/StudyFrameworkPlugin/Public/SFParticipant.h

@@ -42,6 +42,8 @@ public:
 	const TArray<USFCondition*> GetAllConditions() const;
 	int GetCurrentConditionNumber() const;
 	int GetSequenceNumber() const;
+
+	UFUNCTION(BlueprintCallable)
 	FString GetID() const;
 
 	static bool WasParticipantIdAlreadyUsed(FString NewParticipantID);