(Changed in version 2.9.0) The behavior of scanRight
has changed. The previous behavior can be reproduced with scanRight.reverse.
(Changed in version 2.9.0) transpose
throws an IllegalArgumentException
if collections are not uniformly sized.
(Since version 2.10.0) use fold instead
Defines an HTTP header value consisting of a list of values, each of which is a name and optional value.