Bug 31473 Search Engine should not search in working copies that aren't on the build path
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/JavaUI.java
/**
	 * The editor part id of the code snippet editor
	 * (value <code>"org.eclipse.jdt.ui.SnippetEditor"</code>).
	 */
	public static final String ID_SNIPPET_EDITOR= 		"org.eclipse.jdt.ui.SnippetEditor"; 
	/**
	 * The view part id of the Packages view
	 * (value <code>"org.eclipse.jdt.ui.PackageExplorer"</code>).
	 * <p>
	 * When this id is used to access
	 * a view part with <code>IWorkbenchPage.findView</code> or 
	 * <code>showView</code>, the returned <code>IViewPart</code>
	 * can be safely cast to an <code>IPackagesViewPart</code>.
	 * </p>
	 *
	 * @see IPackagesViewPart
	 * @see org.eclipse.ui.IWorkbenchPage#findView(java.lang.String)
	 * @see org.eclipse.ui.IWorkbenchPage#showView(java.lang.String)
	 */ 
	public static final String ID_PACKAGES= 			"org.eclipse.jdt.ui.PackageExplorer"; 
	
	/** 
	 * The view part id of the type hierarchy part.
	 * (value <code>"org.eclipse.jdt.ui.TypeHierarchy"</code>).
	 * <p>
	 * When this id is used to access
	 * a view part with <code>IWorkbenchPage.findView</code> or 
	 * <code>showView</code>, the returned <code>IViewPart</code>
	 * can be safely cast to an <code>ITypeHierarchyViewPart</code>.
	 * </p>