This will hurt on compound primary keys.

[todo]

http/src/Converter/RequestUriToSql.php

Lines 972 to 977 in 156b946

	// @TODO This will hurt on compound primary keys.
	$primaryKey = $metaData->getPrimaryKeyAttributes($modelObject)[0];
	// We need the table to exist in the query in order for the related sort to work.
	// Therefore we add it to comply with this by comparing the primary key to not being NULL.
	$this->relationSearchFields[$modelName][] = [
	$primaryKey, ':', '$$',

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This issue was generated by todo based on a TODO comment in 156b946 when #34 was merged. cc @bakaphp.