diff --git a/arduino-core/src/cc/arduino/utils/network/FileDownloaderCache.java b/arduino-core/src/cc/arduino/utils/network/FileDownloaderCache.java
index b89a862b4..3b51033aa 100644
--- a/arduino-core/src/cc/arduino/utils/network/FileDownloaderCache.java
+++ b/arduino-core/src/cc/arduino/utils/network/FileDownloaderCache.java
@@ -1,6 +1,5 @@
 package cc.arduino.utils.network;
 
-import com.sun.istack.internal.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import processing.app.PreferencesData;
@@ -26,7 +25,7 @@ public class FileDownloaderCache {
   private String eTag;
 
   // BaseNoGui.getSettingsFolder()
-  public FileDownloaderCache(@NotNull String cacheFolder, @NotNull URL remoteURL) {
+  public FileDownloaderCache(String cacheFolder, URL remoteURL) {
     this.remoteURL = remoteURL;
     String[] splitPath = remoteURL.getPath().split("/");
     if (splitPath.length > 0) {
diff --git a/arduino-core/src/cc/arduino/utils/network/HttpConnectionManager.java b/arduino-core/src/cc/arduino/utils/network/HttpConnectionManager.java
index 39a72bb64..ad75c1bfa 100644
--- a/arduino-core/src/cc/arduino/utils/network/HttpConnectionManager.java
+++ b/arduino-core/src/cc/arduino/utils/network/HttpConnectionManager.java
@@ -1,7 +1,6 @@
 package cc.arduino.utils.network;
 
 import cc.arduino.net.CustomProxySelector;
-import com.sun.istack.internal.NotNull;
 import org.apache.commons.codec.binary.Base64;
 import org.apache.commons.httpclient.CircularRedirectException;
 import org.apache.commons.lang3.StringUtils;
@@ -50,7 +49,7 @@ public class HttpConnectionManager {
 
   }
 
-  public HttpURLConnection makeConnection(@NotNull Consumer<HttpURLConnection> beforeConnection)
+  public HttpURLConnection makeConnection(Consumer<HttpURLConnection> beforeConnection)
     throws IOException, NoSuchMethodException, ScriptException, URISyntaxException {
     return makeConnection(this.requestURL, 0, beforeConnection);
   }
@@ -61,8 +60,8 @@ public class HttpConnectionManager {
     return makeConnection(this.requestURL, 0, (c) -> {});
   }
 
-  private HttpURLConnection makeConnection(@NotNull URL requestURL, int movedTimes,
-                                           @NotNull Consumer<HttpURLConnection> beforeConnection) throws IOException, URISyntaxException, ScriptException, NoSuchMethodException {
+  private HttpURLConnection makeConnection(URL requestURL, int movedTimes,
+                                           Consumer<HttpURLConnection> beforeConnection) throws IOException, URISyntaxException, ScriptException, NoSuchMethodException {
     log.info("Prepare http request to " + requestURL);
     if (movedTimes > 3) {
       log.warn("Too many redirect " + requestURL);