Implement JpqlSerializer for JpqlNullIf

[shouwn]

Backgrounds

• In Kotlin JDSL 3.0.0, the Query objects no longer know how to draw themselves as SQL String.
• The Query object is drawn in JPQL String by JpqlSerializer.

Requirements

• Please implement JpqlSerializer that draws JpqlNullIf as a SQL String.
• Please implement a unit test for the implemented class.

Contribution

• Please check if there is an assignee in this issue. And if it don't have an assignee, please change the assignee to yourself.
• Please check the commit convention through the commitlint.config.js file. The commit convention also described in the PR template.
• When you use intellij, please set the code style through the .editorconfig file.
• Please create the PR for develop/3.0.0 as the base branch.
• If you have any questions, please leave comment in Kotlin-JDSL Discord Channel in LINE Open Source

[waveofmymind]

안녕하세요!
assign 부탁드립니다 :)

[shouwn]

Hi @waveofmymind

I haven't checked my mail properly yesterday and today. The email history shows that you requested to assign the ticket, but I don't see them in the current thread. Did you remove your comments because I didn't respond?

If so, this is my fault. If you'd like to contribute, please comment again.

[waveofmymind]

@shouwn
Yes. I requested to be assigned the ticket for JpqlPlus, but since I'm still not familiar with contributing, I intend to first tackle the JpqlNullIf that I've already been assigned.
Once this issue is resolved, I will leave a comment again in the future!
Thank you for your attention.

[shouwn]

Oh, I see. Thank you for your contribution!

[shouwn]

This issue is closed by #405