code: public String getId() {
          if (id != null) {
              return id;
          }
          return getExtraInfo().containsKey("sub") ? (String) getExtraInfo().get("sub") : null;
      }
docs: Getter for the unique Identifier of the user. If this represents a Full User Profile (Management API) the 'id' field will be returned.
  If the value is not present, it will be considered a User Information and the id will be obtained from the 'sub' claim.
  
  @return the unique identifier of the user.