code: public static MappedStatement getExistedMappedStatement(Configuration configuration, String msId) {
          MappedStatement mappedStatement = null;
          try {
              mappedStatement = configuration.getMappedStatement(msId, false);
          } catch (Throwable t) {
              //ignore
          }
          return mappedStatement;
      }
docs: 尝试获取已经存在的在 MS，提供对手写count和page的支持
  
  @param configuration
  @param msId
  @return