title: Apache Ignite - how to check if Key already exists?
body: <p>What is the best approach to check if Key exists in a cache already and if does not - create a new one:</p>
  
  <pre><code>cache.put("key3", 1);
  </code></pre>
  
  <p>I want to increase a Value by 1 if key already exists and if it does not - set it to 1.</p>