Google will give enough hits on the topic, too bad not one which fixed my issue.
Normally you would create an OSB project, create an OSB Configuration project, drag the OSB project on the Configuration project and your done.
In my case it would give the error “Path for project must have only one segment.”
Go to the file
<osb workspace directory>\OSB Configuration\.settings\com.bea.alsb.core.prefs and edit the row 'container.referenced.projects'.
At the end add the name of the project you’re try to link to your Configuration project.
Restart Eclipse and clean (Project > Clean) both the Configuration project and the OSB project.