Comment 7 for bug 1702130

Also affecting jabref (https://build.snapcraft.io/user/JabRef/jabref/97443):

Building jabref
Downloading https://services.gradle.org/distributions/gradle-4.2.1-bin.zip

Exception in thread "main" java.io.IOException: Unable to tunnel through proxy. Proxy returns "HTTP/1.1 407 Proxy Authentication Required"
 at sun.net.www.protocol.http.HttpURLConnection.doTunneling(HttpURLConnection.java:2124)
 at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:183)
 at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1546)
 at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
 at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
 at org.gradle.wrapper.Download.downloadInternal(Download.java:66)
 at org.gradle.wrapper.Download.download(Download.java:51)
 at org.gradle.wrapper.Install$1.call(Install.java:62)
 at org.gradle.wrapper.Install$1.call(Install.java:48)
 at org.gradle.wrapper.ExclusiveFileAccessManager.access(ExclusiveFileAccessManager.java:69)
 at org.gradle.wrapper.Install.createDist(Install.java:48)
 at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:107)
 at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)
./gradlew -Dhttp.proxyHost=snap-proxy.launchpad.net -Dhttp.proxyPort=3128 -Dhttp.proxyUser=SNAPBUILD-97443-1508933192 -Dhttp.proxyPassword=6ee4d054add7418ab1751cf7540bbed7 -Dhttps.proxyHost=snap-proxy.launchpad.net -Dhttps.proxyPort=3128 -Dhttps.proxyUser=SNAPBUILD-97443-1508933192 -Dhttps.proxyPassword=6ee4d054add7418ab1751cf7540bbed7 snapJar jar