Manage UnknownHostException in case scidata service is down.

ChangeLog

+4.0.22 dd/06/2020
+------
+* Manage UnknownHostException in case scidata service is down.
+
+
 4.0.21 05/06/2020
 ------
 * Improve messages about token state.

conf/client/clientMessages.properties

@@ -230,6 +230,8 @@ serviceUnavailableErrorMessageKey=SI service unavailable.
 genericErrorMessageKey=Unable to connect to SI server. 
 connectionTimeoutErrorMessageKey=A timeout occurred while connecting to SI server.\nNomad will automatically switch to internal use. Try again later.
 connectionTimeoutErrorMessageTitle=Getting proposals
+unknownHostMessageKey=Unknown host: 
+ 
 
 parentDirectoryLabel=Parent folder:
 newFolderMessage=new folder...

src/main/java/fr/ill/ics/common/Nomad.java

@@ -35,6 +35,7 @@ import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
 import java.net.SocketTimeoutException;
 import java.net.URL;
+import java.net.UnknownHostException;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
@@ -1235,6 +1236,10 @@ public abstract class Nomad {
 			br.close();
 			JSONParser parser = new JSONParser();
 			object = (JSONObject)parser.parse(jsonString);
+		} catch (UnknownHostException e) {
+			String message = ConfigManager.getInstance().getString("unknownHostMessageKey") + " " + e.getLocalizedMessage();
+			DialogManager.getInstance().nomadMessageDialog(message, "");
+			return null;
 		} catch (SocketTimeoutException e) { // can be thrown by getInputStream
 			DialogManager.getInstance().nomadMessageDialog("connectionTimeoutErrorMessageKey", "connectionTimeoutErrorMessageTitle");
 			return null;
@@ -1244,7 +1249,9 @@ public abstract class Nomad {
 			e.printStackTrace();
 		} finally {
 			try {
-				br.close();
+				if (br != null) {
+					br.close();
+				}
 			} catch (IOException e) {
 				e.printStackTrace();
 			}