#vulnerable code 
                                @Test
    public void testValidMapStatementWithExpression() throws Exception {
        ForLoopStatement statement = transformer.transform("k, v in dictionary.items()");
        Assert.assertEquals(ForLoopStatement.Type.MAP, statement.getType());
        Assert.assertEquals("k v", statement.getVarName());
        Assert.assertEquals("dictionary.items()", statement.getCollectionExpression());
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testValidMapStatementWithExpression() throws Exception {
        ForLoopStatement statement = transformer.transform("k, v in dictionary.items()");
        MapForLoopStatement mapForLoopStatement  = validateMapForLoopStatement(statement);
        Assert.assertEquals("k", mapForLoopStatement.getKeyName());
        Assert.assertEquals("v", mapForLoopStatement.getValueName());
        Assert.assertEquals("dictionary.items()", statement.getCollectionExpression());
    }