Will diagnostic code be part of the LSP protocol diagnostics class?

[chanchiem]

In the official LSP specification, the "Code" parameter is defined as part of the diagnostics class, but it isn't defined in the class here. The "Code" parameter could be used for example to denote the inherent meaning behind the particular diagnostic, such as an error code.

Is this something that is planned to be added? I'll happily create a pull request if this is something that is valid.