Bug in SpecificDiscoveryStore breaks PubSub communication

[KonradBreitsprecherBkd]

For a specific setup, the PubSub communication is failing. Minimal conditions to reproduce the bug are:

• Two publishers, one subscriber (all running autonomous, async)
• The publishers carry the optional label L1
• The single subscriber carries the optional label L1 and the optional label L2
• The publishers are started first, then the subscriber is started

// Start the two publishers first
.\SilKitDemoPublisher.exe -Aa -n Pub1 -f
.\SilKitDemoPublisher.exe -Aa -n Pub2 -f

// Then start the subscriber
.\SilKitDemoSubscriber.exe -aA

// Bug: No reception on the subscriber

The bug can be traced back to the SpecificDiscoveryStore. This is the lookup algorithm that is supposed to improve the matching of publishers and subscribers with labels.