This topic has been addressed in this forum a few times, but I'm still not sure what the correct way is to make rectangular holes in EasyEda (std).

I need such a hole, 10.4mm x 14mm, at an angle of 45 degr as shown here in the 2D photo view.

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I created a solid region in the document layer, edited the points to the exact coordinates, and set type to "Board Cutout", as explained in the documentation. 

My concern is that this hole has squared corners, but JLCPCB says: "Rectangular holes and slots without rounded corners are not supported."

Question is: will JLCPCB reject my project, or will it produce the cutout with correct sizes but with rounded corners. Or do I need to create the solid region with rounded corners? (Then the question would be: how??)