SLF4J-579: Export client packages of slf4j-api in version 1

Fixes https://jira.qos.ch/browse/SLF4J-576

This allows to use the slf4j-api version 2 artifact as drop-in
replacement for slf4j-api version 1 in OSGi environments as well.
slf4j-api can now be wired to bundles that require packages of slf4j-api
in version 1 or 2.

Signed-off-by: Hannes Wellmann <wellmann.hannes1@gmx.net>

pom.xml

@@ -34,9 +34,8 @@
 
   <properties>
     <!-- yyyy-MM-dd'T'HH:mm:ss'Z' -->
-    <project.build.outputTimestamp>2022-12-12T19:19:39Z</project.build.outputTimestamp>    
-    <latest.stable.version>1.7.36</latest.stable.version>
-    <latest.2.version>2.0.0-alpha7</latest.2.version>    
+    <project.build.outputTimestamp>2022-12-12T19:19:39Z</project.build.outputTimestamp>
+    <latest.1.version>1.7.36</latest.1.version>
     <!-- java.util.ServiceLoader requires Java 6 -->
     <jdk.version>8</jdk.version>
     <maven.compiler.source>${jdk.version}</maven.compiler.source>

slf4j-api/pom.xml

@@ -59,6 +59,11 @@
         <configuration>
           <instructions>
             <Import-Package>org.slf4j.spi;version="${range;[===,+);${version;===;${maven_version;${project.version}}}}"</Import-Package>
+            <!-- Export the client/user package of slf4j-api version 1 to make the slf4j-api bundle in version 2 usable for bundles that only import slf4j-1.x -->
+            <_exportcontents><![CDATA[
+              *,\
+              org.slf4j;uses:="org.slf4j.event,org.slf4j.helpers,org.slf4j.spi";version="${latest.1.version}"
+            ]]></_exportcontents>
             <Require-Capability><![CDATA[
               osgi.extender;filter:="(&(osgi.extender=osgi.serviceloader.processor)(version>=1.0.0)(!(version>=2.0.0)))",
               osgi.serviceloader;filter:="(osgi.serviceloader=org.slf4j.spi.SLF4JServiceProvider)";osgi.serviceloader="org.slf4j.spi.SLF4JServiceProvider"