code: JPAPUnitInfo findPersistenceUnitInfo(JPAPuId puId)
      {
          final boolean isTraceOn = TraceComponent.isAnyTracingEnabled();
          if (isTraceOn && tc.isEntryEnabled())
              Tr.entry(tc, "findPersistenceUnitInfo : " + puId);
  
          if (isTraceOn && tc.isDebugEnabled())
              Tr.debug(tc, "Current application list : " + getSortedAppNames());
  
          JPAPUnitInfo rtnVal = null;
          JPAApplInfo applInfo = applList.get(puId.getApplName());
          if (applInfo != null)
          {
              rtnVal = applInfo.getPersistenceUnitInfo(puId.getModJarName(), puId.getPuName());
          } else
          {
              Tr.warning(tc, "APPL_NOT_FOUND_DURING_PU_LOOKUP_CWWJP0010W",
                         puId.getApplName(), puId.getModJarName(), puId.getPuName());
          }
          if (isTraceOn && tc.isEntryEnabled())
              Tr.exit(tc, "findPersistenceUnitInfo : " + rtnVal);
          return rtnVal;
      }
docs: Locate the persistence unit information by application/module/unit name.