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

    pctx.addInput("bNull", Boolean.class);
    pctx.addInput("bTrue", Boolean.class);
    pctx.addInput("bFalse", Boolean.class);
    Map vars = new HashMap() {{
        put("bNull", null);
        put("bTrue", true);
        put("bFalse", false);
    }};

    assertEquals(true, MVEL.executeExpression(MVEL.compileExpression("bNull == empty", pctx), vars));
    assertEquals(false, MVEL.executeExpression(MVEL.compileExpression("bTrue == empty", pctx), vars));
    assertEquals(true, MVEL.executeExpression(MVEL.compileExpression("bFalse == empty", pctx), vars));
  }