Property duplication on overriding property with [JsonPropertyName]

[PSanetra]

Description

On serializing a derived class overridden properties may be duplicated if [JsonPropertyName] is assigned.

Reproduction Steps

Create the following classes:

public class VirtualProperty_TestClass
{
    public virtual string MyString { get; set; }
}

public class OverridePropertyNameInDerivedClass_TestClass : VirtualProperty_TestClass
{
    [JsonPropertyName("my_string")]
    public override string MyString { get; set; }
}

Then serialize an instance of OverridePropertyNameInDerivedClass_TestClass like this:

string serialized = JsonSerializer.Serialize(new OverridePropertyNameInDerivedClass_TestClass()
{
    MyString = "MyValue"
});
Assert.Equal(@"{""my_string"":""MyValue""}", serialized);

Expected behavior

This serialized string should be equal to {"my_string":"MyValue"}.

Actual behavior

This serialized string is equal to {"my_string":"MyValue","MyString":"MyValue"}.

Regression?

No response

Known Workarounds

No response

Configuration

.NET: 8.0.0
OS: Linux
Arch: x64
System.Text.Json: 8.0.0

Other information

Known affected code:
OpenIdConnectConfiguration.Issuer in Microsoft.IdentityModel.Protocols.OpenIdConnect is inherited from BaseConfguration.Issuer in Microsoft.IdentityModel.Tokens

Because of this issue serializing a OpenIdConnectConfiguration instance will create a json object with both an issuer and Issuer property. Some other properties like TokenEndpoint are affected, too.

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Issue Details

---

Description

On serializing a derived class overridden properties may be duplicated if [JsonPropertyName] is assigned.

Reproduction Steps

Create the following classes:

public class VirtualProperty_TestClass
{
    public virtual string MyString { get; set; }
}

public class OverridePropertyNameInDerivedClass_TestClass : VirtualProperty_TestClass
{
    [JsonPropertyName("my_string")]
    public override string MyString { get; set; }
}

Then serialize an instance of OverridePropertyNameInDerivedClass_TestClass like this:

string serialized = JsonSerializer.Serialize(new OverridePropertyNameInDerivedClass_TestClass()
{
    MyString = "MyValue"
});
Assert.Equal(@"{""my_string"":""MyValue""}", serialized);

Expected behavior

This serialized string should be equal to {"my_string":"MyValue"}.

Actual behavior

This serialized string is equal to {"my_string":"MyValue","MyString":"MyValue"}.

Regression?

No response

Known Workarounds

No response

Configuration

.NET: 8.0.0
OS: Linux
Arch: x64
System.Text.Json: 8.0.0

Other information

Known affected code:
OpenIdConnectConfiguration.Issuer in Microsoft.IdentityModel.Protocols.OpenIdConnect is inherited from BaseConfguration.Issuer in Microsoft.IdentityModel.Tokens

Because of this issue serializing a OpenIdConnectConfiguration instance will create a json object with both an issuer and Issuer property. Some other properties like TokenEndpoint are affected, too.

Author:	PSanetra
Assignees:	-
Labels:	area-System.Text.Json, untriaged
Milestone:	-

[eiriktsarpalis]

Appears to be a duplicate of #51165