private function buildAndCondition($operator, $operands)
{
$parts = [];
foreach ($operands as $operand) {
if (is_array($operand)) {
$operand = $this->buildCondition($operand);
}
if (!empty($operand)) {
$parts[] = $operand;
}
}
if (!empty($parts)) {
return [$operator => $parts];
} else {
return [];
}
}