[MSHADE-413] Fix endless loop caused by manipulating shared objects

Maven objects (like `Dependency` or `Model`) returned by Maven must not
be modified. Doing so will result in endless loops or incorrect builds.

src/main/java/org/apache/maven/plugins/shade/mojo/ShadeMojo.java

@@ -1083,14 +1083,20 @@ private void createDependencyReducedPom( Set<String> artifactsToRemove )
             // we'll figure out the exclusions in a bit.
             transitiveDeps.add( dep );
         }
-        List<Dependency> origDeps = project.getDependencies();
 
-        if ( promoteTransitiveDependencies )
+        Model model = project.getOriginalModel();
+
+        // MSHADE-413: Must not use objects (for example `Model` or `Dependency`) that are "owned
+        // by Maven" and being used by other projects/plugins. Modifying those will break the
+        // correctness of the build - or cause an endless loop.
+        List<Dependency> origDeps = new ArrayList<>();
+        List<Dependency> source = promoteTransitiveDependencies ? transitiveDeps : project.getDependencies();
+        for ( Dependency d : source )
         {
-            origDeps = transitiveDeps;
+            origDeps.add( d.clone() );
         }
+        model = model.clone();
 
-        Model model = project.getOriginalModel();
         // MSHADE-185: We will remove all system scoped dependencies which usually
         // have some kind of property usage. At this time the properties within
         // such things are already evaluated.