Trust Anchor entity statement contains 'metadata_policy'

[HarryKodden]

According to the specifications only subordinates MAY have this attribute in their entity statement, trust-anchors may not
It is found that the the Trust Anchor entty statement contains this field (although it is empty) but it should not be there at all.

  "iss": "https://openid-federation-server.example.com",
  "jwks": {
    "keys": [
      {
        "alg": "ES256",
        "crv": "P-256",
        "kid": "jXsTu6F2r7JCd5n87C-HcAXPhGjGHTNqTsi_NczTWyI",
        "kty": "EC",
        "use": "sig",
        "x": "UOKqUk7LF7nhSlHcMSyd-U2bUZZENlP1q7169UYf9P0",
        "y": "kW3o4M24CX5Ei5IMJMFeitK3J5GEFJCpW1Df1xoEx9g"
      }
    ]
  },
  "metadata": {
    "federation_entity": {
      "federation_fetch_endpoint": "https://openid-federation-server.example.com/fetch",
      "federation_historical_keys_endpoint": "https://openid-federation-server.example.com/historical-keys",
      "federation_list_endpoint": "https://openid-federation-server.example.com/list",
      "federation_trust_mark_endpoint": "https://openid-federation-server.example.com/trust-mark",
      "federation_trust_mark_list_endpoint": "https://openid-federation-server.example.com/trust-mark-list",
      "federation_trust_mark_status_endpoint": "https://openid-federation-server.example.com/trust-mark-status"
    }
  },
  "metadata_policy": {}, **<--- THIS SHOULD NOT BE HERE** 
  "sub": "https://openid-federation-server.example.com",
  "trust_mark_issuers": {
    "https://example.edu/trust-mark-types/mannen-met-baarden": [
      "https://openid-federation-server.example.com/tm-issuer"
    ],
    "https://example.edu/trust-mark-types/mannen-met-baarden2": [
      "https://openid-federation-server.example.com/tm-issuer2"
    ]
  },
  "trust_marks": []
}

metadata_policy
OPTIONAL. JSON object that defines a metadata policy, as described in Section 6.1. Only Subordinate Statements MAY include this claim. The metadata policy applies to the Entity that is the subject of this Subordinate Statement as well as to all Entities that are Subordinate to it. Applying to Subordinate Entities distinguishes metadata_policy from metadata, which only applies to the subject itself.