Problem/Bug NoSuchMethodError

My Plugin is a PvP reset plugin that automatically resets a person's equipment depending on a config that is set by the server owner. The problem with this is that I try to use the Material.matchMaterial() method, which works well except that it returns the legacy version of the material, even though the config does not have legacy materials. You can see this in the LegacyProblems.txt. If I try to specify a boolean for match material to return a new Material, which according to
https://hub.spigotmc.org/javadocs/s....html#matchMaterial(java.lang.String,boolean)
is allowed, it gives me the NoSuchMethodError that you can see in the server log file. I'm not sure how to fix this, as I think I've imported everything correctly.
Getting the new version of this material is important because I later use the GetEquipmentSlot() method for determining where an item should go, and for legacy materials that method returns HAND always.

Please help