If I enter the plantuml code below, the notes are not aligned. If you have a lot of participants with notes over their lifeline this will consume a lot of real estate of the diagram. Is there some way to align the two notes?
title Align notes
actor Actor as oper
participant Participant_A as scp
participant Participant_A as ssc
hnote over scp: State_X
hnote over ssc: State_Y