如何在包含函数cakephp 3 orm中使用case

I have this query:

$result = $this->Status
    ->find()
    ->hydrate(false)
    ->contain([
        'Proposals' => function ($q) {
            $pendenteCase = $q->newExpr()->addCase(
                $q->newExpr()->add(['status_id = 6']),
                7,
                'integer'
            );
            $q = $q
                ->select([
                    'Proposals.status_id' => $pendenteCase,
                    'count' => $q->func()->count('Proposals.id'),
                    'ano' => $q->func()->extract('YEAR', 'Proposals.created'),
                    'mes' => $q->func()->extract('MONTH', 'Proposals.created')
                ])
                ->group(['Proposals.status_id', 'ano', 'mes'])
                ->order(['ano' => 'ASC', 'mes' => 'ASC']);
            return $q;
        }
    ]
)
->where(function ($exp, $q) {
    return $exp->notIn('id', [6, 5]);
});

But I got this error:

You are required to select the "Proposals.status_id" field(s)

How Can I do this works? Because I need that status_id 6 is counted with the status_id 7.