Fixes Or Enhances

Add the omitzero Tag:

• It allows you to ignore the subsequent validations if the value of a field is empty
• If the field is a pointer and the pointer is nil, ignore the subsequent validations
• If the field is a pointer and the pointer is not nil, but the content value of the pointer is zero, the subsequent validations will be ignored

Make sure that you've checked the boxes below before you submit PR:

• Tests exist or have been written that cover this particular change.

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