Lost Passover Scripture?

Justin Martyr, a Greek Christian from the 2nd Century and one of the first Christian apologists, wrote a "dialogue" with a Jew named Trypho sometime around 150 AD. In this massive book, Justin claims that the Jews have purposely changed the scriptures because of Christianity and quotes from a number of verses that were either changed or taken out of the Jewish texts. One of these is a speech by Ezra (or Esdras) concerning Passover.

“They have deleted the following passage in which Ezra expounded the law of the Passover: 'And Ezra said to the people: This Passover is our Savior and refuge. And if you have understood, and it has entered into your hearts, that we are about to humiliate Him on a cross, and afterwards hope in Him, then this place will never be forsaken, saith the Lord of hosts. But if you will not believe Him, nor listen to His teaching, you will be the laughing-stock of the Gentiles”
--Justin Martyr, Dialogue with Trypho, 72:1

This same passage is quoted by Lactantius in the beginning of the third century.

“In Esdras it is thus written: "And Ezra said to the people, This passover is our Saviour and our refuge. Consider and let it come into your heart, that we have to abase Him in a figure; and after these things we will hope in Him, lest this place be deserted for ever, saith the Lord God of hosts. If you will not believe Him, nor hear His announcement, ye shall be a derision among the nations."
--Lactantius, Divine Institutions, 4.18
(and again in Epitome of the Divine Institutes, 48)

It seems ludicrous to suggest that Justin, a learned scholar and philosopher, who is composing an argument from an intellectual and scholastic Greek background, and speaking toward Jews who would know the history of their texts better than your average Pagan or Gentile, would invent verses and then argue that they were taken out of scripture. What is even more strange is that no one seems to have called Justin's bluff if he did make it up as Christians were fond of doing with heretical or bogus texts, verses, and theologies from the get-go.

But if such verses did exist, where do they come from? From the Biblical Ezra? From one of the many Apocryphal or Apocalyptic Ezra books? Lactantius may have simply relied on the passage from Justin for his quotes, but if so, this still doesn't answer where Justin got his from. And if it really existed in a manuscript, why do we have no evidence of it? Surely the Jews could not have so completely erased it that nothing is left today. They evidently left sufficient evidence for Justin to make his claims.

Does anyone have insight on the origins of this anomaly?