Fix log4j-to-slf4j JPMS and OSGi descriptors

Due to the upgrade from SLF4J 1.7.x to 2.x, the JPMS and OSGi
descriptors of `log4j-to-slf4j` suffer from these shortcomings:

 * the JPMS descriptor uses a filebased `slf4j-api` module name (instead
   of `org.slf4j`,
 * the OSGi descriptor accepts a restricted range of SLF4J versions: [2,
   3). Since `slf4j-api` 2.x is technically just a minor version update
   of `slf4j-api` 1.7.x, we should use an extended range of [1.7, 3).

Closes #1983.

Author: ppkarwasz

log4j-to-slf4j/pom.xml

@@ -32,11 +32,16 @@
     <!--
       ~ OSGi and JPMS options
       -->
-    <slf4j.support.bound>3</slf4j.support.bound>
+    <slf4j.support.range>[1.7,3)</slf4j.support.range>
     <bnd-extra-package-options>
       <!-- This bridge also support SLF4J 2.x -->
-      org.slf4j.*;version="${range;[==,${slf4j.support.bound})}"
+      org.slf4j.*;version="${slf4j.support.range}"
     </bnd-extra-package-options>
+    <bnd-extra-module-options>
+      <!-- The module descriptor is in `META-INF/versions/9`
+           BND 6.x can not find it -->
+      org.slf4j;substitute="slf4j-api"
+    </bnd-extra-module-options>
   </properties>
   <dependencies>
     <dependency>

src/changelog/.2.x.x/fix_log4j_to_slf4j_descriptor.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns="http://logging.apache.org/log4j/changelog"
+       xsi:schemaLocation="http://logging.apache.org/log4j/changelog https://logging.apache.org/log4j/changelog-0.1.2.xsd"
+       type="fixed">
+  <issue id="1983" link="https://github.com/apache/logging-log4j2/pull/1983"/>
+  <description format="asciidoc">
+    Fix `log4j-to-slf4j` JPMS and OSGi descriptors.
+  </description>
+</entry>