title: replace null or empty data in string builder with some message
body: <p>I have a string builder and it contains some data.I want to ensure whenever there is a null or empty("") data in it, i want to replace it with some message e.g not available. This is a huge data and i cannot go and replace each and every String.
  Following is a snippet of code :</p>
  
  <pre><code>Stringbuilder sb = new Stringbuilder();
  String a = "10";
  String b = 13;
  sb.append("entity.id=").append(a).append("entity.value=").append(b);
  sb.toString;
  </code></pre>
  
  <p>So whenever entity.id or entity."ANYTHING" equals "null" or is empty, it should be replaced with a message like entity.id= not available</p>