Plant UML template - https://www.plantuml.com/plantuml/uml

template.puml

@startuml
title <size:50> Title of your diagram

skinparam sequence {
ArrowColor DeepSkyBlue
ActorBorderColor DeepSkyBlue
LifeLineBorderColor blue
LifeLineBackgroundColor #A9DCDF

ParticipantBorderColor DeepSkyBlue
ParticipantBackgroundColor DodgerBlue
ParticipantFontSize 17
ParticipantFontColor #A9DCDF
ParticipantPadding 270
ParticipantFontSize 17

ActorBackgroundColor aqua
ActorFontColor DeepSkyBlue
ActorFontSize 17
ActorFontName Aapex

SequenceMessageAlign direction

}

actor Bob as b
participant "Participant 1" as v
|||
b-->>v: "Hello world"
note right
<code>
Please note not all values are required refer to 

{
  "jsonproperty" : "hello"
}
 
</code>
endnote
|||
alt Alt flow
b-->>v: "Hello world - 2"
end
|||
|||
alt Alt flow 2
    b-->>v: "Hello world - 3"
    note right
    <code>
        Some code
    </code>
    endnote    
end
|||
|||
@enduml