code: public static void restorePropertyAsNeeded(final String propName, final String oldPropValue, final String newPropValue) {
          java.security.AccessController.doPrivileged(new java.security.PrivilegedAction<Object>() {
              @Override
              public Object run() {
                  if (oldPropValue == null) {
                      System.clearProperty(propName);
                  } else if (!oldPropValue.equalsIgnoreCase(newPropValue)) {
                      System.setProperty(propName, oldPropValue);
                  }
                  return null;
              }
          });
          if (tc.isDebugEnabled())
              Tr.debug(tc, "Restore property " + propName + " to previous value: " + oldPropValue);
      }
docs: This method restore the property value to the original value.
  
  @param propName
  @param oldPropValue
  @param newPropValue