code: public static String getUsername(String token) {
  		String accessTokenPayload = token.substring(token.indexOf(".") + 1, token.lastIndexOf(".") );
  		byte[] decoded = Base64.getMimeDecoder().decode(accessTokenPayload);
  		String output = new String(decoded);
  		Map<String,Object> myMap = new HashMap<String, Object>();
  		String result = "unknown";
  
  		ObjectMapper objectMapper = new ObjectMapper();
  		try {
  			myMap = objectMapper.readValue(output, HashMap.class);
  			if(myMap.get("sub") instanceof String) {
  				result = (String) myMap.get("sub");
  			}
  		} catch (IOException e) {
  			e.printStackTrace();
  		}
  		return result;
  	}
docs: Username from a given JWT Token
  @param token JWT Token
  @return  Username from JWT Token.