code: @Override
  	public synchronized boolean revokeAccess(Principal caller, AccessControl aclEntry)
  	{
  		if (aclEntry == null)
  			return false;
  
  		Principal principal = aclEntry.getPrincipal();
  
  		if (principal == null)
  			return false;
  
  		Set<AccessControl> set = this.entries.get(aclEntry.getPrincipal());
  		if (set == null || set.isEmpty())
  			return false;
  		boolean r = set.remove(aclEntry);
  
  		this.entries.put(principal, set);
  
  		return r;
  	}
docs: /*
  (non-Javadoc)
  
  @see nyla.solutions.core.security.data.Acl#revokeAccess(java.security.
  Principal, nyla.solutions.core.security.data.AccessControl)