goja-core/src/main/java/goja/core/kits/stream/StreamUtil.java
public static void copy(Reader input, OutputStream output) throws IOException {
        copy(input, output, Const.DEFAULT_ENCODING);
    }
public static void copy(Reader input, OutputStream output) throws IOException {
        copy(input, output, Const.DEFAULT_ENCODING);
    }
Copies reader to output stream using buffer.