[java] batch copy input to multiple streams

Author: joerg1985

java/src/org/openqa/selenium/io/MultiOutputStream.java

@@ -31,6 +31,14 @@ public MultiOutputStream(OutputStream mandatory, OutputStream optional) {
     this.optional = optional;
   }
 
+  @Override
+  public void write(byte[] b, int off, int len) throws IOException {
+    mandatory.write(b, off, len);
+    if (optional != null) {
+      optional.write(b, off, len);
+    }
+  }
+
   @Override
   public void write(int b) throws IOException {
     mandatory.write(b);