To represent readonly lists in a class diagram, connect the class the List is defined in with the class of its Type using the 'Is Associated With' pointer. On the line, use the name of the Field. Instead of a 1 at the end of the pointer use a star * to indicate that there are many of that type. After the name of the Field, add the add the <readonly> modifier.
In order to add the angle brackets to the "Is Associated With" pointer, use the html encoding < and >
Additionally, lists are represented as being folded in as shown in the diagram below.
The html encoding does not need to be used for folded in lists.