java.net.UnknownHostException: www.springframework.org
   at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:177)
   at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
   at java.net.Socket.connect(Socket.java:525)
   at java.net.Socket.connect(Socket.java:475)
   at sun.net.NetworkClient.doConnect(NetworkClient.java:163)
   at sun.net.www.http.HttpClient.openServer(HttpClient.java:394)
   at sun.net.www.http.HttpClient.openServer(HttpClient.java:529)
   at sun.net.www.http.HttpClient.<init>(HttpClient.java:233)
   at sun.net.www.http.HttpClient.New(HttpClient.java:306)
   at sun.net.www.http.HttpClient.New(HttpClient.java:323)
   at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:860)
   at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:839)
   at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:726)
   at org.netbeans.modules.xml.retriever.impl.URLResourceRetriever.getInputStreamOfURL(URLResourceRetriever.java:126)
   at org.netbeans.modules.xml.retriever.impl.URLResourceRetriever.retrieveDocument(URLResourceRetriever.java:99)
   at org.netbeans.modules.xml.retriever.catalog.impl.CatalogModelImpl.getModelSource(CatalogModelImpl.java:248)
   at org.netbeans.modules.xml.retriever.catalog.impl.CatalogModelImpl.doGetModelSource(CatalogModelImpl.java:233)
   at org.netbeans.modules.xml.retriever.catalog.impl.CatalogModelImpl.getModelSource(CatalogModelImpl.java:168)
   at org.netbeans.modules.xml.schema.completion.util.DefaultModelProvider.getCompletionModel(DefaultModelProvider.java:115)
   at org.netbeans.modules.xml.schema.completion.util.DefaultModelProvider.getModels(DefaultModelProvider.java:90)
   at org.netbeans.modules.xml.schema.completion.util.CompletionContextImpl.initModels(CompletionContextImpl.java:673)
   at org.netbeans.modules.xml.schema.completion.CompletionQuery.getCompletionItems(CompletionQuery.java:104)
   at org.netbeans.modules.xml.schema.completion.CompletionQuery.query(CompletionQuery.java:82)
   at org.netbeans.spi.editor.completion.support.AsyncCompletionTask.run(AsyncCompletionTask.java:218)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:641)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1123)