problem whit Gradle in Flutter android studio 3.2 working behind a proxy

I'm working behind a proxy and i have this problem when i run muy flutter app in android studio 3.2

Launching lib\main.dart on LGMS323 in debug mode...
Initializing gradle...
Finished with error: Exit code 1 from: D:\Android\Flutter\Mis_Proyectos\flutter_app\android\gradlew.bat -v:
Downloading https://services.gradle.org/distributions/gradle-4.4-all.zip   

Exception in thread "main" java.net.UnknownHostException: services.gradle.org
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:673)
    at sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:173)
    at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
    at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:264)
    at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:367)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:191)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1138)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1032)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:177)
    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:58)
    at org.gradle.wrapper.Download.download(Download.java:44)
    at org.gradle.wrapper.Install$1.call(Install.java:61)
    at org.gradle.wrapper.Install$1.call(Install.java:48)
    at org.gradle.wrapper.ExclusiveFileAccessManager.access(ExclusiveFileAccessManager.java:65)
    at org.gradle.wrapper.Install.createDist(Install.java:48)
    at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:128)
    at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)

And when I change in android/gradle/wraper/gradle-graper.properitis:

distributionUrl=https://services.gradle.org/distributions/gradle-4.4-all.zip

for

distributionUrl=D:\Android\Gradle/gradle-4.6-all.zip

this happens:

Launching lib\main.dart on LGMS323 in debug mode...
Initializing gradle...
Finished with error: Exit code 1 from: D:\Android\Flutter\Mis_Proyectos\flutter_app22222222\android\gradlew.bat -v:
Exception in thread "main" java.lang.NullPointerException
    at org.gradle.wrapper.PathAssembler.getDistName(PathAssembler.java:84)
    at org.gradle.wrapper.PathAssembler.getDistribution(PathAssembler.java:40)
    at org.gradle.wrapper.Install.createDist(Install.java:44)
    at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:128)
    at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)