title: How to replace a function on a Liferay native portlet
body: <p>I am making a change to a native Liferay portlet, that comes with Liferay Intallation. How can I change a function to my own implementation by a hook or similar approach?</p>
  
  <p>I have read how to make pre and post conditions and how to make new implementation of an interface, but I don't know how to just replace random function inside random class at a portlet that I want to keep otherwise as it is originally.</p>