Merge pull request #438 from jgangemi/jae/issue-434

- added overloaded 'uploadAsset' method

src/main/java/org/kohsuke/github/GHRelease.java

@@ -3,6 +3,7 @@
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.net.URL;
 import java.util.Arrays;
 import java.util.Date;
@@ -125,12 +126,16 @@ static GHRelease[] wrap(GHRelease[] releases, GHRepository owner) {
      * handling of the HTTP requests to github's API.
          */
     public GHAsset uploadAsset(File file, String contentType) throws IOException {
+        return uploadAsset(file.getName(), new FileInputStream(file), contentType);
+    }
+
+    public GHAsset uploadAsset(String filename, InputStream stream, String contentType) throws IOException {
         Requester builder = new Requester(owner.root);
 
         String url = format("https://uploads.github.com%s/releases/%d/assets?name=%s",
-                owner.getApiTailUrl(""), getId(), file.getName());
+                owner.getApiTailUrl(""), getId(), filename);
         return builder.contentType(contentType)
-                .with(new FileInputStream(file))
+                .with(stream)
                 .to(url, GHAsset.class).wrap(this);
     }