public void testEmptyOperatorOnInteger() {
    ParserConfiguration conf = new ParserConfiguration();
    ParserContext pctx = new ParserContext( conf );
    pctx.setStrictTypeEnforcement(true);
    pctx.setStrongTyping(true);

    pctx.addInput("nullInt", Integer.class);
    pctx.addInput("zero", Integer.class);
    pctx.addInput("nonZero", Integer.class);
    Map vars = new HashMap() {{
        put("nullInt", null);
        put("zero", 0);
        put("nonZero", 42);
    }};

    assertEquals(true, MVEL.executeExpression(MVEL.compileExpression("nullInt == empty", pctx), vars));
    assertEquals(true, MVEL.executeExpression(MVEL.compileExpression("zero == empty", pctx), vars));
    assertEquals(false, MVEL.executeExpression(MVEL.compileExpression("nonZero == empty", pctx), vars));
  }