first investigation shows (from a new OH 2.1 stable on Windows with Astro binding installed from PaperUI):
C:\openHAB2\userdata\tmp\mvn\org\eclipse\smarthome\binding\org.eclipse.smarthome.binding.astro\0.9.0.b5
org.eclipse.smarthome.binding.astro-0.9.0.b5.jar
file size: 91.557 bytes
#Generated by Maven
#Tue Jun 27 11:19:54 CEST 2017
version=0.9.0.b5
so… it looks ok (it seems so)
I think that b5 is ok. It looks like it refers to the 0.9.0 ESH versioning (no connection to OH2 beta 5)
On my linux system running OH 2.2.0 snapshot:
/var/lib/openhab2/tmp/mvn/org/eclipse/smarthome/binding/org.eclipse.smarthome.binding.astro/0.9.0-SNAPSHOT/
org.eclipse.smarthome.binding.astro-0.9.0-SNAPSHOT.jar
file size: 91.581 bytes
#Generated by Maven
#Tue Jun 27 04:49:43 EDT 2017
version=0.9.0-SNAPSHOT