code: public static NKey fromPublicKey(char[] publicKey) {
          byte[] raw = decode(publicKey);
          int prefix = raw[0] & 0xFF;
  
          if (!checkValidPublicPrefixByte(prefix)) {
              throw new IllegalArgumentException("Not a valid public NKey");
          }
  
          Type type = NKey.Type.fromPrefix(prefix);
          return new NKey(type, publicKey, null);
      }
docs: Create an NKey object from the encoded public key. This NKey can be used for verification but not for signing.
  
  @param publicKey the string encoded public key
  @return the new Nkey