Being new to Keys and the way sponge uses .offer, Im not sure what I am doing wrong here.

public ItemStack generatePickaxe() {
	ItemStack pickaxe = ItemStack.of(ItemTypes.IRON_PICKAXE, 1);
	pickaxe.offer(Keys.DISPLAY_NAME,Text.of(TextColors.GOLD,"Wool Remover"));
	pickaxe.offer(Keys.UNBREAKABLE, true);
	return pickaxe;

This will not build because the parameters for the thrird offer are seemingly incorrect. The Sponge documentation states that Keys.BREAKABLE_BLOCK_TYPES is of type BlockType. What am I doing wrong?

Keys.BREAKABLE_BLOCK_TYPES is not a BlockType but a Set<BlockType>
so for example using

pickaxe.offer(Keys.BREAKABLE_BLOCK_TYPES, Sets.newHashSet(BlockTypes.WOOL));

should work ^^

Wonderful! Thank you Blue

For others who stumble upon this answer if you want to set more than one type then use:

pickaxe.offer(Keys.BREAKABLE_BLOCK_TYPES, Sets.newHashSet(BlockTypes.WOOL,BlockTypes.OTHER));