[SLING-7194] Document that AdapterManager sorts AdapterFactory implementations lowest ranking first

• Type: Task
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: API 2.16.4
• Fix Version/s: API 2.18.0
• Component/s: Extensions
• Assignee: Stefan Seifert
• Reporter: Stefan Seifert
• Created: 12/Oct/17 15:16
• Updated: 19/Mar/18 06:19
• Resolved: 12/Dec/17 10:41

Description

the current implementation of AdapterManager uses a AdapterFactoryDescriptorMap to sort the AdapterFactory implementations found.

this is done using a TreeMap with the ServiceReference as key. ServiceReference implements a compareTo.

according to its documentation the default implementation sorts with service-ranking lowest-first/service id highest-first:
https://osgi.org/javadoc/r6/core/org/osgi/framework/ServiceReference.html#compareTo(java.lang.Object)

when picking a service from multiple ones using BundleContext.getService, the service with hightest service ranking/lowest service id is returned.

i would expect the same from the AdapterManager implementation - if multiple implementations match pick that one with highest ranking/lowest service id.

Issue Links

• relates to: SLING-2630 Cannot have multiple Adapter Factories configured to have same adapter / adaptable combination
• supercedes: SLING-7196 sling-mock: Make sure SlingContext.registerAdapter can overlay built-in adaptions
• links to: GitHub Pull Request #1