code: @Function
      public static boolean acceptClientToken(GSSContext context, byte[] token) {
          try {
              if (!context.isEstablished()) {
                  byte[] nextToken = context.acceptSecContext(token, 0, token.length);
                  return nextToken == null;
              }
              return true;
          } catch (GSSException ex) {
              throw new RuntimeException("Exception accepting client token", ex);
          }
      }
docs: Accept a client token to establish a secure communication channel.
  @param context GSSContext for which a connection has been established to the remote peer
  @param token the client side token (client side, as in the token had
  to be bootstrapped by the client and this peer uses that token
  to update the GSSContext)
  @return a boolean to indicate whether the token was used to successfully
  establish a communication channel