in src/main/java/com/googlesource/gerrit/plugins/serverconfig/ServerConfigServlet.java [148:153]
private static String diff(File oldFile, File newFile) throws IOException {
RawText oldContext = new RawText(oldFile);
RawText newContext = new RawText(newFile);
UnifiedDiffer differ = new UnifiedDiffer();
return differ.diff(oldContext, newContext);
}