code: public static void addImport( Instance instance, String componentOrFacetName, Import imp ) {
  
  		Collection<Import> imports = instance.getImports().get( componentOrFacetName );
  		if(imports == null) {
  			imports = new LinkedHashSet<Import> ();
  			instance.getImports().put( componentOrFacetName, imports );
  		}
  
  		if( ! imports.contains( imp ))
  			imports.add( imp );
  	}
docs: Adds an import to an instance (provided this import was not already set).
  @param instance the instance whose imports must be updated
  @param componentOrFacetName the component or facet name associated with the import
  @param imp the import to add