code: @Test public void specifically_exclude_control_chars() throws UnsupportedEncodingException {
    for (int i=0; i < 32; ++i) {
      final Map<String,String> inMap=new HashMap<String,String>(1);
      final String s=Arrays.toString(Character.toChars(i));
      inMap.put("a",s);
      final String data=encode(inMap);
      assertFalse(data.contains(s));
      final Map<String,String> outMap=new HashMap<String,String>(1);
      decode(outMap,data);
      assertEquals(1,outMap.size());
      assertEquals(s,outMap.get("a"));
    }
  }
  