code: public void setPuName(String puName)
      {
          // re-initialize puName only if it has not been set to avoid
          //   overriding valid relative puName defined in annotation/dd.
          if (ivPuName == null || ivPuName.length() == 0) // d442457
          {
              ivPuName = puName;
              reComputeHashCode(); // d416151.3.9
          }
      }
docs: Persistence unit name setter.