AADB2C Claims Transformation for JSON from Federated Identity - azure-ad-b2c-custom-policy

Question

I am writing IEF policy integrating with Federated Identity Provider. IDP returns claims in id_token as JSON. when I use claims mapping custom_attributes in output claims, I am getting AAD Exception as
An unexpected type "System.Collections.Generic.List1[System.Collections.Generic.KeyValuePair2[System.String,System.Object]]" was encountered of the claim with claim type id "custom_attributes"
here is my claim mapping:
<OutputClaim ClaimTypeReferenceId="custom_attributes" PartnerClaimType="custom_attributes"/>
claim Schema as:
<ClaimType Id="custom_attributes">
<DisplayName>custom_attributes</DisplayName>
<DataType>string</DataType>
<UserHelpText>Add help text here</UserHelpText>
</ClaimType>
id_token looks like below:
{
"custom_attributes":{
"emailAddress": "someone#example.com",
"displayName": "Someone",
"id" : 6353399
}
}
<OutputClaimsTransformations>
<OutputClaimsTransformation ReferenceId="CreateRandomUPNUserName" />
<OutputClaimsTransformation ReferenceId="CreateUserPrincipalName" />
<OutputClaimsTransformation ReferenceId="CreateAlternativeSecurityId" />
<OutputClaimsTransformation ReferenceId="GetRequestorIdClaimFromJsonClaimsTransformation" />
</OutputClaimsTransformations>
claim Schema as
<ClaimsTransformation Id="GetRequestorIdClaimFromJsonClaimsTransformation" TransformationMethod="GetClaimFromJson">
<InputClaims>
<InputClaim ClaimTypeReferenceId="custom_attributes" TransformationClaimType="inputJson" />
</InputClaims>
<InputParameters>
<InputParameter Id="claimToExtract" DataType="string" Value="id"/>
</InputParameters>
<OutputClaims>
<OutputClaim ClaimTypeReferenceId="requestorid" TransformationClaimType="extractedClaim" />
</OutputClaims>
</ClaimsTransformation>

Answer 1

I found a solution to the problem and added it here
https://stackoverflow.com/questions/68086538/why-i-am-gettting-error-in-outputclaim-for-json-object-key-value-pair