code: private synchronized boolean isUsed(final T candidate) {
          LOG.debug("Checking if used: " + candidate);
  
          LOG.debug("Used? " + m_usedServerIds.contains(candidate));
  
          return (m_usedServerIds.contains(candidate));
      }
docs: Returns whether a given server is already in use.
  
  @param candidate
  The URI of the server to check.
  
  @return Whether a given server is already in use.