prevent from NPE, add a multi get returning list of pair of (key maps)

[worldline-messaging]

if(rec.bins!=null) { to prevent from NullPointerException ( you can pass an empty set as parameter of the query )

multiQueryL is better when you want to keep the order of the keys passed as parameter. With a map you loose the order in the result.

For the WriteSettings, i prefere to send key by default.

Blocking is just a question of choice.

[soro]

That null check actually seems to be necessary - should probably have been spelled out in their docs that they simply return a null instead of an empty collection in case you request no bins.
I think it makes more sense to add a method that takes a CanBuildFrom instead of a concrete List instance.