code: protected PGPPublicKey findPublicKey(InputStream publicKey, KeyFilter<PGPPublicKey> keyFilter ) {
      LOGGER.trace("findPublicKey(InputStream, KeyFilter<PGPPublicKey>)");
      LOGGER.trace("Public Key: {}, Key Filter: {}", publicKey == null ? "not set" : "set", keyFilter == null ? "not set" : "set");
      return retrievePublicKey(readPublicKeyRing(publicKey), keyFilter);
    }
docs: reads the public key from the given stream
  
  @param publicKey
  the input key stream
  @param keyFilter
  the filter to apply
  @return the matching PGP public key