logback-classic OSGi bundle doesn't export logback implementation packages. These packages need to be imported by bundles implementing custom logback Appenders etc.

The problem is most likely caused a misconfiguration of maven-bundle-plugin in logback-classic POM. Current configuration:

<instructions>
<Export-Package>ch.qos.logback.classic.*</Export-Package>
<Export-Package>org.slf4j.impl;version=1.5.6</Export-Package>
<Import-Package>sun.reflect;resolution:=optional,
javax.jms;resolution:=optional,
*
</Import-Package>

<Bundle-RequiredExecutionEnvironment>J2SE-1.5</Bundle-RequiredExecutionEnvironment>
</instructions>

Suggested configuration:

<instructions>
<Export-Package>ch.qos.logback.classic.*,
org.slf4j.impl;version=1.5.6
</Export-Package>
<Import-Package>sun.reflect;resolution:=optional,
javax.jms;resolution:=optional,
*
</Import-Package>

<Bundle-RequiredExecutionEnvironment>J2SE-1.5</Bundle-RequiredExecutionEnvironment>
</instructions>

Second Export-Package declaration seems to override the first one.