public FormState::has($property)
Determines if an arbitrary property is present.
Parameters
string $property: Properties are often stored as multi-dimensional associative arrays. If $property is a string, it will return isset($storage[$property]). If $property is an array, each element of the array will be used as a nested key. If $property = ['foo', 'bar'] it will return isset($storage['foo']['bar']).
Overrides FormStateInterface::has
File
core/lib/Drupal/Core/Form/FormState.php, line 930