adding a ProgressListener interface, tho it still needs to be called from somewhere...

src/main/java/net/schmizz/sshj/xfer/AbstractFileTransfer.java

@@ -29,6 +29,8 @@ public abstract class AbstractFileTransfer {
     private volatile ModeGetter modeGetter = defaultModeGetter;
     private volatile ModeSetter modeSetter = defaultModeSetter;
 
+    private volatile ProgressListener progressListener;
+
     public void setModeGetter(ModeGetter modeGetter) {
         this.modeGetter = (modeGetter == null) ? defaultModeGetter : modeGetter;
     }
@@ -45,4 +47,12 @@ public abstract class AbstractFileTransfer {
         return this.modeSetter;
     }
 
+    public ProgressListener getProgressListener() {
+        return progressListener;
+    }
+
+    public void setProgressListener(ProgressListener progressListener) {
+        this.progressListener = progressListener;
+    }
+
 }

src/main/java/net/schmizz/sshj/xfer/FileTransfer.java

@@ -33,4 +33,8 @@ public interface FileTransfer {
 
     void setModeSetter(ModeSetter modeSetter);
 
+    ProgressListener getProgressListener();
+
+    void setProgressListener(ProgressListener listener);
+
 }

src/main/java/net/schmizz/sshj/xfer/ProgressListener.java

@@ -0,0 +1,11 @@
+package net.schmizz.sshj.xfer;
+
+public interface ProgressListener {
+
+    void started(int item, boolean isDir);
+
+    void progressed(long done, long total);
+
+    void completed(int item);
+
+}