code: public void distrust(OpenPgpV4Fingerprint fingerprint)
              throws IOException {
          store.setTrust(getJid(), fingerprint, OpenPgpTrustStore.Trust.untrusted);
      }
docs: Mark a key as {@link OpenPgpStore.Trust#untrusted}.
  
  @param fingerprint {@link OpenPgpV4Fingerprint} of the key to mark as untrusted.
  
  @throws IOException IO error