Update sourcecode.adoc

src/docs/asciidoc/jme3/advanced/sourcecode.adoc

@@ -388,7 +388,6 @@ public class TerrainTrackControl extends AbstractControl {
     public Control cloneForSpatial(Spatial spatial) {        
         TerrainTrackControl control = new TerrainTrackControl();        
         //TODO: copy parameters to new Control        
-        control.setSpatial(spatial);        
         return control;    
     }