Content-Type: text/html
Content-Length: 510

Empty string vs void:
Json: "" vs null
Json (void as string): "" vs ""
Json (void as null): "" vs null
Length: 0 vs 0
Double: 0 vs 0
Base64: "" vs ""
Hash compatibility: "" ""
Non-empty string not hash compatible: Type: parser.runtime,
Source: key,
Comment: is 'string', it has no elements
Absent method empty string error: Type: parser.runtime,
Source: something,
Comment: string method not found
Absent method non-empty string error: Type: parser.runtime,
Source: something,
Comment: string method not found