Spring Expression Language:: Look up in a map for every value in a collection

[vladiva]

I've following code:

@Test
   public void testCollection()
  {
    List<String> l= new ArrayList<String>();
    l.add("S1");
    l.add("S2");
    Map<String, String> m = new HashMap<String, String>();
    m.put("S1","M1");
    m.put("S2","M2");
    
   StandardEvaluationContext evaluationContext = new StandardEvaluationContext();
    evaluationContext.setVariable("l",l);
    evaluationContext.setVariable("m",m);
    
    ExpressionParser expressionParser = new SpelExpressionParser();
    
    String expression1 = "#l.![#this]";
    // This one prints S1,S2
    System.out.println(expressionParser.parseExpression(expression1).getValue(evaluationContext,String.class));
    
    String expression2 = "#l.![#m[#this]]";
    // This one prints null, null and I expect M1,M2
    System.out.println(expressionParser.parseExpression(expression2).getValue(evaluationContext,String.class));
  } 

The question is why expression2 is evaluated to null,null and not M1,M2 or generally how do I get a collection of values projected by looking up in a map using collection entries as keys?

[shenzhenguy]

I tried this "#m.?[#l.contains(key)].keySet()".
but cannot work