UUF: How to ignore all null values

### Type of issue

Missing information

### Description

Why is there no way to ignore all null values when deserializing JSON? This used to exist! I shouldn't have to make my properties nullable if I don't actually expect nulls and a default value is perfectly acceptable if I receive one and ignore it!

### Page URL

https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/ignore-properties

### Content source URL

https://github.com/dotnet/docs/blob/main/docs/standard/serialization/system-text-json/ignore-properties.md

### Document Version Independent Id

db1ef743-6f31-a509-4676-f22d4847792d

### Article author

@gewarren

### Metadata

* ID: b7aa3b68-ffe0-8bdf-b6f4-b99672086a92
* Service: **dotnet-fundamentals**

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