I stumbled onto something interesting today. The only places where the Hebrew word "the idolatrous priests" (hachemarim הכמרים) occurs are Zephaniah 1:4, 2 Kings 23:5, and Hosea 10:5. This chapter from Kings tells us about Josiah's response to God's word; and Zephaniah is introduced with this information in verse 1: "The word of the Lord which came to Zephaniah...in the days of Josiah"
"I will cut off every trace of Baal from this place, The names of the idolatrous priests with the pagan priests..." Zeph 1:4
"Then he removed the idolatrous priests..." 2 Kings 23:5