code: public Object execute(final Map<Object, Object> iArgs) {
      if (attribute == null)
        throw new OCommandExecutionException("Cannot execute the command because it has not been parsed yet");
  
      final OClassImpl cls = (OClassImpl) getDatabase().getMetadata().getSchema().getClass(className);
      if (cls == null)
        throw new OCommandExecutionException("Source class '" + className + "' not found");
  
      cls.setInternalAndSave(attribute, value);
      renameCluster();
      return null;
    }
docs: Execute the ALTER CLASS.