Java's setRequestProperty supported, with a caveat
Thursday, April 20, 2006 8:46:43 AM
Opera's Java implementation will now support HTTPUrlConnection.setRequestProperty but for security reasons (to prevent so called "request smuggling attacks") it will not permit sending several headers. These headers include "Host", "Content-length" and "Transfer-Encoding".
This is the same security policy we apply to the XMLHttpRequest object and I believe the Flash plugin does the same thing for its ActionScript implementation.