code: public void loadAllPlugins() throws FlowTriggerDependencyPluginException {
      final File pluginDir = new File(this.pluginDir);
      for (final File dir : pluginDir.listFiles()) {
        loadDependencyPlugin(dir);
      }
      //reset thread context loader so that other azkaban class will be loaded with the old
      // classloader
      Thread.currentThread().setContextClassLoader(this.prevClassLoader);
    }
docs: Initialize all dependency plugins.
  todo chengren311: Current design aborts loadAllPlugins if any of the plugin fails to be
  initialized.
  However, this might not be the optimal design. Suppose we have two dependency plugin types
  - MySQL and Kafka, if MySQL is down, then kafka dependency type will also be unavailable.