IDPSSODescriptor attributes not exported

I am running the example ExampleIdentityProvider and the ExportMetadata.aspx page.

When I export the ADFS configuration I would expect to see the attribute
WantAssertionsSigned=“true” on the IDPSSODescriptor element.

Am I doing something incorrect or is my understanding flawed ?

WantAssertionsSigned is a property of the SPSSODescriptor.
It’s informing partner IdPs that your SP wants SAML assertions signed.
We set WantAssertionsSigned if the PartnerIdentityProviderConfiguration.WantAssertionSigned flag is set in the SP’s SAML configuration.