Prevent BaseValidatorWriter.write call if only empty optional params

If there are only optional parameters in the method signature, the method
is not called anymore if all of those parameters are empty. This prevents
some difficult cases where the validator would say that it writes
something to the writer when in reality it wouldn't. The validator writers
have to write something when they are called.

If user wants to make a writer to be called everytime, he/she has to make
a new validator writer. Previously user had on option to make similar case
with optional parameters.