Checkstyle: Add override property in DesignForExtension module

While performing checks for class design it is mandatory to provide javadoc, we can skip override methods from this checkstyle check.

Sample error:
Class 'ABC' looks like designed for extension (can be subclassed), but the method 'xyz' does not have javadoc that explains how to do that safely. If class is not designed for extension consider making the class 'ABC' final or making the method 'xyz' static/final/abstract/empty, or adding allowed annotation for the method.

<module name="DesignForExtension">
<property name="ignoredAnnotations"
value="After, AfterClass, Before, BeforeClass, Test, Property, Override"/>
</module>