on an unrelated note, Gavroche is not the only one who uses Javert’s dialogue tune - the policemen who arrest Valjean use it too:
Tell his reverence your story
Let us see if he’s impressed
You were lodging there last night
You were the honest Bishop’s guest.
And then, out of Christian goodness
When he learned about your plight
You maintain he made a present
of this silver -
and then the Bishop cuts them off before they can finish it.