pthid not assigned correctly when conneting implicitly to public did

[TimoGlastra]

When connecting implicitly to a public did and sending a didexchange request the pthid of the request message is assigned to the public did of the other agent (did:sov:xxx)

However, according to the didexchange protocol the pthid must be a DID URL pointing to the service that is used for the implicit invitation:

When a request responds to an implicit invitation, its ~thread.pthid MUST contain a DID URL that resolves to the specific service on a DID document that contains the invitation.

Example request message (see ~thread.pthid):

{
  "@type": "did:sov:BzCbsNYhMrjHiqZDTUASHg;spec/didexchange/1.0/request",
  "@id": "885c84e3-4dcb-4a25-b9d6-08c15f2082e7",
  "~thread": {
    "thid": "885c84e3-4dcb-4a25-b9d6-08c15f2082e7",
    "pthid": "did:sov:Ehx3RZSV38pn3MYvxtHhbQ"
  },
  "did_doc~attach": {
    "@id": "8577d83d-62b6-4d83-bf63-ec9a469f66a6",
    "mime-type": "application/json",
    "data": {
      "base64": "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",
      "jws": {
        "header": {
          "kid": "did:key:z6Mkj14Mshy7bSLrTW78u3tHpAsMdttDBwz1ymZbTopZ3U5J"
        },
        "protected": "eyJhbGciOiAiRWREU0EiLCAia2lkIjogImRpZDprZXk6ejZNa2oxNE1zaHk3YlNMclRXNzh1M3RIcEFzTWR0dERCd3oxeW1aYlRvcFozVTVKIiwgImp3ayI6IHsia3R5IjogIk9LUCIsICJjcnYiOiAiRWQyNTUxOSIsICJ4IjogIlE1UWZJTDB3LWo2Q254ZXdwRzdXaVNnZ3RQMlJHS3Ata1p0MzRqcmF0UFUiLCAia2lkIjogImRpZDprZXk6ejZNa2oxNE1zaHk3YlNMclRXNzh1M3RIcEFzTWR0dERCd3oxeW1aYlRvcFozVTVKIn19",
        "signature": "wnEjsOPXaFmv-ssQs7Q_dkpp04G3eRs-jrGzQt9YYoSsQLHdfzqo9Yuc3EuYZFENNLK60dBuWtjGA7AACFA0Dg"
      }
    }
  },
  "did": "9M1DtMrSEfkHXUBLkayweY",
  "label": "Animo Community Agent"
}