code: public IntrospectionResponse callIntrospection(String accessToken, String[] scopes, String subject, String clientCertificate)
      {
          // Create a request for /api/auth/introspection API.
          IntrospectionRequest request = new IntrospectionRequest()
              .setToken(accessToken)
              .setScopes(scopes)
              .setSubject(subject)
              .setClientCertificate(clientCertificate);
  
          try
          {
              // Call Authlete's /api/auth/introspection API.
              return mApi.introspection(request);
          }
          catch (AuthleteApiException e)
          {
              // The API call failed.
              throw apiFailure("/api/auth/introspection", e);
          }
      }
docs: Call Authlete's {@code /api/auth/introspection} API.