Bug 4240 Can't edit class path entry (1GKEPIF)
There is no way to edit an existing entry for a library on the Java Build Path project properties page (other than editing the .classpath file directly). NOTES: EG (9/22/2001 11:42:11 AM) this is particularly annoying for variables. we should have an Edit button when a variable is selected.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/NewVariableEntryDialog.java
private final Object[] EMPTY= new Object[0];
	
		public Object[] getChildren(Object parentElement) {
			if (parentElement instanceof File) {
				File[] children= ((File) parentElement).listFiles();
				if (children != null) {
					return children;
				}
			}