Disallow empty Identifiers

[mversic]

At the moment it is allowed to create empty Name, DomainId, AccountId, etc. Should we continue to allow empty string identifiers or should we forbid them. What about using Option?

It should be noted that empty string is a well defined identifier

[ales-tsurko]

@mversic @appetrosyan could you clarify this issue?

It should be noted that empty string is a well defined identifier

So Name type is allowed to have empty string? But in which case AccountId can be empty? And is it possible, for example, to have AccountId like ""@""? So we should require non-empty strings for some types? I mean, should we forbid, for example, using empty name and domainID for AccountId, or forbid name to be empty for DomainId (because it's the only field), but still allow Name to be empty?

[appetrosyan]

To me it seems that the sole purpose of the Name struct is to encapsulate that some valid strings are invalid identifiers. As such an empty identifier is not a valid Name. Thus, we should allow an empty constString, but not an empty Name.