Collection->List since order is important

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1524707 13f79535-47bb-0310-9956-ffa450edef68
Set->LinkedHashSet as order needs to be retained

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1524719 13f79535-47bb-0310-9956-ffa450edef68