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Unexpected nullability for get-only properties for json schema produced by STJ #131602
Description
Description
When a property doesn't have a setter, its info will have IsSetNullable set to true, and then the JsonSchemaExporter will make the schema nullable.
Reproduction Steps
#nullable enable
using System;
using System.Collections.Generic;
using System.Text.Json;
using System.Text.Json.Schema;
Console.WriteLine(JsonSchemaExporter.GetJsonSchemaAsNode(JsonSerializerOptions.Default, typeof(C)));
class C
{
public IEnumerable<string> Values => [];
public string SingleValueGetOnly { get; }
public string SingleValueGetSet { get; set; }
}Expected behavior
The Values and SingleValueGetOnly properties shouldn't be marked nullable.
Actual behavior
{
"type": [
"object",
"null"
],
"properties": {
"Values": {
"type": [
"array",
"null"
],
"items": {
"type": [
"string",
"null"
]
}
},
"SingleValueGetOnly": {
"type": [
"string",
"null"
]
},
"SingleValueGetSet": {
"type": "string"
}
}
}Regression?
No response
Known Workarounds
No response
Configuration
No response
Other information
I think the summary of where the behavior comes from is:
A property without a setter will have its info with IsSetNullable = true (the nullability info is reported as "unknown" - but IsSetNullable will consider unknown as if it's nullable)
Reacted by Copilot
Activity
[-]Unexpected nullability get-only properties for json schema produced by STJ[/-][+]Unexpected nullability for get-only properties for json schema produced by STJ[/+]dotnet-policy-service commentedon Jul 30, 2026
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Fix JSON schema nullability for readonly properties (#132271)