Allow for compiling with Java 21 (#4161)

* Support Java 17 and 21, default compilation to Java 17 class files,
  use maven.compiler.release instead of source and target
* Add profile "j21" to compile to Java 21 class files
* Upgrade SAT to 0.16.0, adapt code which breaks build with new SAT
  checks
* Use model-specific-profile to pin xtend to Java 17

Signed-off-by: Holger Friedrich <mail@holger-friedrich.de>

bundles/org.openhab.core/src/main/java/org/openhab/core/internal/scheduler/CronSchedulerImpl.java

@@ -107,7 +107,7 @@ void removeSchedule(CronJob s) {
             for (Iterator<Cron> cron = crons.iterator(); cron.hasNext();) {
                 final Cron c = cron.next();
 
-                if (c.target == s) {
+                if (c.target.equals(s)) {
                     cron.remove();
                     c.schedule.cancel(true);
                 }

bundles/pom.xml

@@ -276,6 +276,10 @@
           <exists>model.profile-marker</exists>
         </file>
       </activation>
+      <properties>
+        <!-- workaround for Java 21 build, necessary until xtend supports Java 21 -->
+        <maven.compiler.release>17</maven.compiler.release>
+      </properties>
       <dependencies>
         <dependency>
           <groupId>org.openhab.core.bom</groupId>

pom.xml

@@ -64,17 +64,14 @@
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-    <oh.java.version>17</oh.java.version>
-    <maven.compiler.source>${oh.java.version}</maven.compiler.source>
-    <maven.compiler.target>${oh.java.version}</maven.compiler.target>
-    <maven.compiler.compilerVersion>${oh.java.version}</maven.compiler.compilerVersion>
+    <maven.compiler.release>17</maven.compiler.release>
 
     <bnd.version>7.0.0</bnd.version>
     <commons.net.version>3.7.2</commons.net.version>
     <eea.version>2.3.0</eea.version>
     <karaf.compile.version>4.4.5</karaf.compile.version>
     <karaf.tooling.version>4.4.5</karaf.tooling.version>
-    <sat.version>0.15.0</sat.version>
+    <sat.version>0.16.0</sat.version>
     <slf4j.version>2.0.7</slf4j.version>
     <xtext.version>2.34.0</xtext.version>
     <spotless.version>2.38.0</spotless.version>
@@ -670,7 +667,7 @@ Import-Package: \\
             <configuration>
               <rules>
                 <requireJavaVersion>
-                  <version>[17.0,18.0)</version>
+                  <version>[17.0,18.0),[21.0,22.0)</version>
                 </requireJavaVersion>
               </rules>
             </configuration>
@@ -845,5 +842,11 @@ Import-Package: \\
         </pluginManagement>
       </build>
     </profile>
+    <profile>
+      <id>j21</id>
+      <properties>
+        <maven.compiler.release>21</maven.compiler.release>
+      </properties>
+    </profile>
   </profiles>
 </project>