docs: public void addDescriptor(JdbcConnectionDescriptor jcd)
      {
          synchronized (jcdMap)
          {
              if (jcdMap.containsKey(jcd.getPBKey()))
              {
                  throw new MetadataException("Found duplicate connection descriptor using PBKey " +
                          jcd.getPBKey() + ", remove the old descriptor first, before add the new one. " + jcd);
              }
              jcdMap.put(jcd.getPBKey(), jcd);
              // only if the jcdAlias was not found, put the new PBKey,
              // because we don't want to replace the original PBKey with
              // automatic generated descriptors PBKey's - see method getDescriptor(PBKey key)
              if (!jcdAliasToPBKeyMap.containsKey(jcd.getJcdAlias()))
              {
                  jcdAliasToPBKeyMap.put(jcd.getJcdAlias(), jcd.getPBKey());
              }
              if (log.isDebugEnabled()) log.debug("New descriptor was added: " + jcd);
          }
      }