Prevent NPE from occurring

[birariro]

Hi,
I think NotNull Message looks better than NPE.

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[mp911de]

How did you encounter a null pointer at ValidationErrors? Do you have a stack trace handy?

[birariro]

There is no reason for an NPE to occur in ValidationErrors.
But if you look at the existing code
Assert.notNull(source, "Entity must not be null");

Since there is a logic to check null, I thought we considered the possibility of it occurring.