[trait] Set default value to null when accept empty
[trait] Set default value to null when accept empty

Cottser/DrupalConsole,dkgndec/DrupalConsole,dkgndec/DrupalConsole,dkgndec/DrupalConsole,revagomes/DrupalConsole,revagomes/DrupalConsole,revagomes/DrupalConsole,Cottser/DrupalConsole,Cottser/DrupalConsole