A person in possession of real property, claiming an estate of freehold therein or an unexpired term of not less than 10 years, or a person who has conveyed such property or any interest therein with covenants of title or warranty, upon which he may be liable, may, if he or those under whom he claims or those claiming under him have been in uninterrupted possession of such property for 4 years or more, bring an action in the Superior Court, or in the District Court in the county or district respectively in which said real property lies, by complaint setting forth his estate, describing the premises and averring that an apprehension exists that persons named in the complaint, or persons unknown, claim by continued and uninterrupted use for 20 years or more, by grant, prescription, custom or in any other way, an easement through or on such real property adverse to the estate of the said plaintiff and that such apprehension creates a cloud upon the title and depreciates the market value of such property; and praying that such persons be summoned to show cause why they should not bring an action to determine their legal rights in and to such easement over or upon said real estate. If such supposed claimants are unknown, the plaintiff or his attorney shall so allege under oath, but the truth of the allegation shall not after the decree has been filed be denied for the purpose of defeating the title established thereby.   [PL 1971, c. 117, §3 (AMD).]