Using maven-gae-plugin behind proxy

I'm using maven-gae-plugin 0.9.2 happily except one issue: it can not use proxy to connect to internet, and every time i call the run goal it will throw an exception:

INFO: Unable to access https://appengine.google.com/api/updatecheck?runtime=java&release=1.6.1&timestamp=1323730393&api_versions=[ '1.0'] java.net.ConnectException: Connection timed out: connect at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:529) at com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:564) at com.sun.net.ssl.internal.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:141) at sun.net.NetworkClient.doConnect(NetworkClient.java:163) at sun.net.www.http.HttpClient.openServer(HttpClient.java:395) at sun.net.www.http.HttpClient.openServer(HttpClient.java:530) at sun.net.www.protocol.https.HttpsClient.(HttpsClient.java:272) at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:329) ....

i tried use <jvmflags> under <configuration> to give my proxy address but with no luck, and Google didn't give me any useful info too. Any ideas?

Problem solved, <jvmflags> should be <jvmFlags>