toBoolNullable method
Converts a case-insensitive string of 'true' or 'false' to a boolean. Returns null if the string is empty or not 'true' or 'false'.
Implementation
bool? toBoolNullable() {
if (toLowerCase() == 'true') {
return true;
} else if (toLowerCase() == 'false') {
return false;
}
return null;
}