OneToOne relationship showing an issue with empty `$timespans` if no invoices exist for the timespans, concerning https://github.com/doctrine/doctrine2/pull/180

entities.php

class Company {
	/**
	 * @var Timespan[]
	 * @ORM\OneToMany(targetEntity="Timespan", mappedBy="company", cascade={"persist", "remove"})
	 */
	protected $timespans;
}

class Timespan {
	/**
	 * @var Company
	 * @ORM\ManyToOne(targetEntity="Company", inversedBy="timespans")
	 * @ORM\JoinColumn(name="company_id", referencedColumnName="id", nullable=false)
	 * @Assert\NotNull
	 */
	protected $company;

	/**
	 * @var Invoice
	 * @ORM\OneToOne(targetEntity="Invoice", mappedBy="timespan", cascade={"persist", "remove"})
	 */
	protected $invoice;
}

class Invoice {
	/**
	 * @var Timespan
	 * @ORM\OneToOne(targetEntity="Timespan", inversedBy="invoice")
	 * @ORM\JoinColumn(name="timespan_id", referencedColumnName="id", nullable=false)
	 * @Assert\NotNull
	 */
	protected $timespan;
}