code: @Nonnull
    public static EChange setPropertyValue (@Nonnull final String sKey, @Nullable final String sValue)
    {
      boolean bChanged;
      if (sValue == null)
      {
        // Was something removed?
        bChanged = removePropertyValue (sKey) != null;
      }
      else
      {
        final String sOld = IPrivilegedAction.systemSetProperty (sKey, sValue).invokeSafe ();
        bChanged = sOld != null && !sValue.equals (sOld);
        if (LOGGER.isDebugEnabled () && bChanged)
          LOGGER.debug ("Set system property '" + sKey + "' to '" + sValue + "'");
      }
      return EChange.valueOf (bChanged);
    }
docs: Set a system property value under consideration of an eventually present
  {@link SecurityManager}.
  
  @param sKey
  The key of the system property. May not be <code>null</code>.
  @param sValue
  The value of the system property. If the value is <code>null</code>
  the property is removed.
  @return {@link EChange}