[API Proposal]: Add freezing APIs to JsonTypeInfo

[eiriktsarpalis]

Background and motivation

Following up on #76540, this tracks the proposal to add user browsable locking APIs for the System.Text.Json metadata types. It follows the API shape applied to JsonSerializerOptions in #74431.

API Proposal

namespace System.Text.Json.Metadata;

public partial static class JsonTypeInfo
{
 public bool IsReadOnly { get; }
 public void MakeReadOnly();
}

API Usage

var resolver = new DefaultJsonTypeInfoResolver
{
 Modifiers =
 {
 static typeInfo =>
 {
 if (typeInfo.IsReadOnly)
 {
 // type is locked for further modification, exit the modifier
 return;
 }

 if (typeInfo.Type == typeof(MySpecialPoco))
 {
 typeInfo.CreateObject = () => new MySpecialPoco("defaultValue");
 // prevent subsequent modifiers/resolvers from further modifying this contract
 typeInfo.MakeReadOnly(); 
 }
 }
 }
};

Alternative Designs

No response

Risks

No response

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Issue Details

---

Background and motivation

Following up on #76540, this tracks the proposal to add user browsable locking APIs for the System.Text.Json metadata types. It follows the API shape applied to JsonSerializerOptions in #74431.

API Proposal

namespace System.Text.Json.Metadata;

public partial static class JsonTypeInfo
{
 public bool IsReadOnly { get; }
 public void MakeReadOnly();
}

API Usage

var resolver = new DefaultJsonTypeInfoResolver
{
 Modifiers =
 {
 static typeInfo =>
 {
 if (typeInfo.IsReadOnly)
 {
 // type is locked for further modification, exit the modifier
 return;
 }

 if (typeInfo.Type == typeof(MySpecialPoco))
 {
 typeInfo.CreateObject = () => new MySpecialPoco("defaultValue");
 // prevent subsequent modifiers/resolvers from further modifying this contract
 typeInfo.MakeReadOnly(); 
 }
 }
 }
}

Alternative Designs

No response

Risks

No response

Author:	eiriktsarpalis
Assignees:	eiriktsarpalis
Labels:	area-System.Text.Json, api-ready-for-review
Milestone:	8.0.0