This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Apparently "indexed" implements the "indexed property design pattern for a multi-valued property from the JavaBean specification" on the containing type.
(where Id is replaced with the name of the multi-valued property and Type is data type of your single valued property). So you would have to use getId() on the containing type to obtain an array of your "collection". There should be a containing type as every XML document only has a single root element.