The sample of chapter 5.9 is not working.
I reduce the problem to:
@startuml
:foo1;
-> OK You can put text on arrows
also be on several lines
and **very** long...;
:foo2;
-[#green ,dashed]-> Error You can put text on arrows
also be on several lines
and **very** long...;
:foo5;
@enduml
http://www.plantuml.com/plantuml/png/hO-x2W8n44NxVCK5kw0B2ZO6P1ih2siHYz6Cgn1dP9Bu-7kpVeFjkN0Ejy-5hDHxSgkBwZousHgxBVPQSIR1enOKVXUeWCpqbHsbh3ZnI38_sIWXtOJR817UD_Bn7abbwBek_BIBfZrC1cCMJ2FbAyTZwsoQqFwSMWRNiyJnq1S0