In Oracle Service Bus 12c you can use the For-Each action to iterate multiple elements in your message.
While developing a service with For-Each functionality in Service Bus 12c I discovered that there are some subtle changes in the naming of the properties since 10g + 11g.
It took me half an hour to find out what I did wrong, documentation was not really helpful so hopefully this will spare you the trouble :)
In 11g the configuration looks like (screenshot from the OSB 11g Development Cookbook):
In 12c the configuration would look more like this: