Load plugin classes based on column separated list of plugin names.

        Returns dict with plugin name as key and class as value.

def load_sub_plugins_from_str(cls, plugins_str):
        """
        Load plugin classes based on column separated list of plugin names.

        Returns dict with plugin name as key and class as value.

        """
        plugin_classes = {}
        if plugins_str:
            for plugin_name in plugins_str.split(":"):
                pc = load_plugin(plugin_name, MONITOR_DEFAULT_PLUGIN_MODULE)
                plugin_classes[plugin_name] = pc
        return plugin_classes