Concurrency Issue in YarepGroup when adding new member

[baszero]

For websites with high traffic the following method can cause concurrency issues (resulting in corrupt group.xml) as it is not synchronized:

security/src/impl/java/org/wyona/security/impl/yarep/YarepGroup.java

Line 194 in 13dabc3

public void addMember(Item item) throws AccessManagementException {

Possible solution:
The variable memberUserIDs should be created like this:

List<String> memberUserIDs = Collections.synchronizedList(new ArrayList<String>());

I suspect there are many locations in the Yanel code with similar concurrency issues...