Fix path errors while analyzing packages referencing ${java.home}

Some packages (e.g., Javassist) refere ${java.home} in <systemPath> of their dependencies. This commit add "java.home" to the passthrough properties list and prevent maven from complaining such paths are not absolute.

Signed-off-by: Fuminobu TAKEYAMA <[email protected]>

src/main/java/org/spdx/sbom/gradle/maven/PropertiesForPom.java

@@ -29,7 +29,7 @@ public abstract class PropertiesForPom {
 
   PropertiesForPom() {}
 
-  private static final List<String> JAVA_PROP_KEYS = List.of("java.version");
+  private static final List<String> JAVA_PROP_KEYS = List.of("java.version",  "java.home");
 
   @Lazy
   public Properties get() {