here i found variable FName NotifyName;
And function
virtual FString GetNotifyName_Implementation() const override;
But i am not able to get NotifyName.
I am not sure is it right.
class ANIMGRAPHRUNTIME_API UAnimNotify_PlayMontageNotify : public UAnimNotify
{
GENERATED_UCLASS_BODY()
The node you looking at is defined at \Engine\Source\Editor\AnimGraph\Public\K2Node_PlayMontage.h
From here you can find out that montage is starting by call on UAnimInstance* - AnimInstance->Montage_Play() so AnimInstance is important; Looking at UAnimInstance code you may find there are two public delegates declared:
/** Called when a montage hits a 'PlayMontageNotify' or 'PlayMontageNotifyWindow' begin */
FPlayMontageAnimNotifyDelegate OnPlayMontageNotifyBegin;
/** Called when a montage hits a 'PlayMontageNotify' or 'PlayMontageNotifyWindow' end */
FPlayMontageAnimNotifyDelegate OnPlayMontageNotifyEnd;