Weird missing constraint with Logback under Eclipse

I have a开发者_如何学JAVA feature-based launch configuration for an Eclipse RCP product. The feature includes ch.qos.logback.classic, ch.qos.logback.core 0.9.29, and org.slf4j.api 1.6.1. "Validate plugins" shows this error:

Could not find matching capability for Require-Capability: generic; filter="(&(generic=org.slf4j.impl.StaticLoggerBinder)(&(version>=1.6.0)(!(version>=1.7.0))))"

even though ch.qos.logback.classic exports org.slf4j.impl 1.6.1 and I can see StaticLoggerBinder.class in the .jar file. What might the problem be?

---

This is a guess: the "Require-Capability" is an OSGi 4.3 feature that corresponds to a "Provide-Capability". Logback doesn't have any such manifest header. https://github.com/ceki/logback/blob/master/logback-classic/pom.xml#L339