code: @Override
      public boolean updatePolicy(String name, String newDocument)
      throws PolicyIndexException {
  
          writeLock.lock();
          try {
              logger.debug("Updating policy named: " + name);
              if (doDelete(name)) {
                  doAdd(name, newDocument);
                  return true;
              } else {
                  // delete failed
                  return false;
              }
          } finally {
              writeLock.unlock();
          }
      }
docs: /*
  (non-Javadoc)
  @see
  org.fcrepo.server.security.xacml.pdp.data.PolicyIndex#updatePolicy(java.lang.String,
  java.lang.String)