Once this is fixed and released, we should revert this PR.
microsoftgraph/msgraph-metadata#697

Updated the description here. Should be Odata action not function. Functions do not have request bodies as the parameters are in the path.

Also, point of note is that, if requestBody.required = false the OAS does not emit the required property in the requestBody schema.

According to the spec.

Determines if the request body is required in the request. Defaults to false.

So what we should do is set it to true when required parameters are present...

Trying to retrieve the annotations in-lined in the Action parameters fails to retrieve the Org.OData.Core.V1.OptionalParameter annotation using the extensions from the Edm lib.

var annotations =  model.FindVocabularyAnnotationsIncludingInheritedAnnotations(parameter);

<Parameter Name="transitive" Type="Edm.Boolean" Nullable="false">
  <Annotation Term="Org.OData.Core.V1.OptionalParameter" />
</Parameter>

Checking with the OData team to check for its support.