code: public static NKey fromSeed(char[] seed) {
          DecodedSeed decoded = decodeSeed(seed); // Should throw on bad seed
  
          if (decoded.bytes.length == ED25519_PRIVATE_KEYSIZE) {
              return new NKey(Type.fromPrefix(decoded.prefix), null, seed);
          } else {
              try {
                  return createPair(Type.fromPrefix(decoded.prefix), decoded.bytes);
              } catch (Exception e) {
                  throw new IllegalArgumentException("Bad seed value", e);
              }
          }
      }
docs: Creates an NKey object from a string encoded seed. This NKey can be used to sign or verify.
  
  @param seed the string encoded seed, see {@link NKey#getSeed() getSeed()}
  @return the Nkey