In order to use Filtering Feature of rich:dataTable with some custom filtering
functions and controls you should use the next available attributes on columns:
filterExpression - Attribute which allows to define expression
evaluated to boolean value. This expression should check whether the object
satisfies filtering condition or not.
filterMethod - Attribute which should be defined with method binding.
This method should accept on Object parameter and return a boolean value.
Thus, this method also should be used to check whether the object satisfies
filtering condition or not.
In the next simple example we use filterMethod and filterExpression for the first
and second columns filtering correspondingly.