Topology descriptors should support references to externalized provider configuration to promote ease of sharing provider configurations across cluster topologies and Knox instances.
- Define external config content format (the same as today, but a separate document with a <gateway/> root)
- Define external config reference format in topology.xml
- Modify code to resolve external config references, and process them the same as the current in-line <gateway/> content
- Includes determining how externalized provider config changes are propagated to deployed topologies.