log4j-over-slf4j contains this packages:

• org.apache.log4j
• org.apache.log4j.helpers
• org.apache.log4j.spi
• org.apache.log4j.xml

but only exports org.apache.log4j (from [1]):

Implementation-Title: log4j-over-slf4j
Bundle-SymbolicName: log4j.over.slf4j
Bundle-Name: log4j-over-slf4j
Bundle-Vendor: SLF4J.ORG
Export-Package: org.apache.log4j;version=${log4j.version}
Import-Package: org.slf4j;version=${slf4j.api.minimum.compatible.version}, org.slf4j.helpers;version=${slf4j.api.minimum.compatible.version}, org.slf4j.spi;version=${slf4j.api.minimum.compatible.version}

This creates problems in OSGi when some code uses classes from this packages.

To fix this issues all packages should be exported. Manifest should look like this:

Implementation-Title: log4j-over-slf4j
Bundle-SymbolicName: log4j.over.slf4j
Bundle-Name: log4j-over-slf4j
Bundle-Vendor: SLF4J.ORG
Export-Package: org.apache.log4j;version=${log4j.version},org.apache.log4j.helpers;version=${log4j.version},org.apache.log4j.spi;version=${log4j.version},org.apache.log4j.xml;version=${log4j.version}
Import-Package: org.slf4j;version=${slf4j.api.minimum.compatible.version}, org.slf4j.helpers;version=${slf4j.api.minimum.compatible.version}, org.slf4j.spi;version=${slf4j.api.minimum.compatible.version}

[1]: https://github.com/ceki/slf4j/blob/master/log4j-over-slf4j/src/main/resources/META-INF/MANIFEST.MF