code: public final void fileCopy(URL in, File out) throws IOException {
  		assert in != null;
  		try (InputStream inStream = in.openStream()) {
  			try (OutputStream outStream = new FileOutputStream(out)) {
  				final byte[] buf = new byte[FILE_BUFFER];
  				int len;
  				while ((len = inStream.read(buf)) > 0) {
  					outStream.write(buf, 0, len);
  				}
  			}
  		} finally {
  			getBuildContext().refresh(out);
  		}
  	}
docs: Copy a file.
  
  @param in input file.
  @param out output file.
  @throws IOException on error.