code: public static Action getAndCheckAction(EntityDataModel entityDataModel, String actionName) {
          int namespaceLastIndex = actionName.lastIndexOf('.');
          String namespace = actionName.substring(0, namespaceLastIndex);
          String simpleActionName = actionName.substring(namespaceLastIndex + 1);
          Schema schema = entityDataModel.getSchema(namespace);
          if (schema == null) {
              throw new ODataSystemException("Could not find schema in entity data model with namespace: " +
                      namespace);
          }
          Action action = schema.getAction(simpleActionName);
          if (action == null) {
              throw new ODataSystemException("Action not found in entity data model: " + actionName);
          }
          return action;
      }
docs: Gets the action by the specified name, throw an exception if no action with the specified name
  exists.
  
  @param entityDataModel The entity data model.
  @param actionName      The name of action.
  @return the Action instance specified by given actionName.