Fix nullable entity types

[SgtPooki]

Just flagging - we should fix these types for nullable fields by marking them as optional

Originally posted by @silent-cipher in #175 (comment)

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we need to do this across all entity types

[BigLep]

@SgtPooki : is this something that needs to be done before GA?

[SgtPooki]

@BigLep not necessarily.. but it's a small and easy fix that should be done to prevent bugs. i'll tag with help wanted and good first issue