#vulnerable code 
                                @Test
    public void testValidStatement() throws Exception {
        ForLoopStatement statement = transformer.transform("x in collection");
        Assert.assertEquals(ForLoopStatement.Type.LIST, statement.getType());
        Assert.assertEquals("x", statement.getVarName());
        Assert.assertEquals("collection", statement.getCollectionExpression());
    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testValidStatement() throws Exception {
        ForLoopStatement statement = transformer.transform("x in collection");
        ListForLoopStatement listForLoopStatement  = validateListForLoopStatement(statement);
        Assert.assertEquals("x", listForLoopStatement.getVarName());
        Assert.assertEquals("collection", listForLoopStatement.getCollectionExpression());
    }