SAML2 IDP metadata missing NameIDMappingService elements should not error on save

The NameIDMappingService element in the metadata of a remote IDP is not a required element according to the SAML2 spec and OpenAM loads IDP metadata without this element without issue but when in the Services tab of the loaded metadata and hitting Save, OpenAM shows an error box in the console:

Error
Entity descriptor "idpentity" under realm "/" has invalid syntax.

Where idpentity is the entity ID of the loaded metadata and the following is seen in the container logs:

DefaultValidationEventHandler: [ERROR]: a required field "Location" is missing an object 

     Location:  obj: com.sun.identity.saml2.jaxb.metadata.impl.NameIDMappingServiceElementImpl@4653aaf2

To workaround this issue, add a URL into the "NameID Mapping" field at the bottom of the Services page (based on one of the values from the other service location entries) and Save.

Even without this workaround, the changes made to the Services page appear to be applied even though it generates the error.