Nullable Annotation

If true, value will be set to null only if it is one of:

1. Empty string
2. null
3. Empty array
4. Integer 0
5. Float 0.0
6. Boolean false
7. String "0"

This will use the PHP's built in empty construct.

This annotation default to true, and using false might have sense on on overridden properties.

Example usage:

@Nullable

Example of overriding nullable state:

// On base class
@Nullable
// On inherited property
@Nullable(false)