Do not add 'required' if not set and false wanted

The 'required' property of a 'Param' is optional and defaults to false.
Thus there is no reason for adding it when it was not set and the user wants it to be false.

Bug: 61761
Change-Id: I2b2fae5d2d8b1dac2ad2e1a965d9ba5bd7372eef