code: protected String readACLOwner(String cid, Map<String, SortedSet<TempPropertyData>> properties)
        throws IllegalACLException, IOException
     {
        SortedSet<TempPropertyData> ownerValues = properties.get(Constants.EXO_OWNER.getAsString());
        if (ownerValues != null)
        {
           try
           {
              return ValueDataUtil.getString(ownerValues.first().getValueData());
           }
           catch (RepositoryException e)
           {
              throw new IOException(e.getMessage(), e);
           }
        }
        else
        {
           throw new IllegalACLException("Property exo:owner is not found for node with id: " + getIdentifier(cid));
        }
     }
docs: Read ACL owner.
  
  @param cid - node id (used only in exception message)
  @param properties - Property name and property values
  @return ACL owner
  @throws IllegalACLException
  @throws IOException