Bug 80833 [Import/Export] Import exisiting should pre-check for project already in workspace
While it is good that it lets you import projects in the default workspace location, it should not let you select projects that already exist in the workspace (since importing such a project will fail). When searching for .project files in the file system, it could use IWorkspaceRoot.findFilesForLocation followed by checking IFile.exists() to filter out .project files for existing projects.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/wizards/datatransfer/WizardProjectsImportPage.java
/**
	 * Method used for test suite.
	 * @return CheckboxTreeViewer the viewer containing all the projects found 
	 */
	public CheckboxTreeViewer getProjectsList() {
		return projectsList;
	}
	
	/**
	 * Retrieve all the projects in the current workspace.
	 * 
	 * @return IProject[] array of IProject in the current workspace
	 */
	private IProject[] getProjectsInWorkspace(){
		if (wsProjects == null)
			wsProjects = IDEWorkbenchPlugin.getPluginWorkspace().getRoot().getProjects();
		return wsProjects;
	}
	/**
	 * Get the array of valid project records that can be imported 
	 * from the source workspace or archive, selected by the user.
	 * If a project with the same name exists in both the source workspace and the 
	 * current workspace, it will not appear in the list of projects to import and 
	 * thus cannot be selected for import.
	 *   
	 * @return ProjectRecord[] array of projects that can be imported into the workspace
	 */
	private ProjectRecord[] getValidProjects(){
		List validProjects = new ArrayList();
		for (int i = 0; i < selectedProjects.length; i++){