If you’re updating from 1.10.2 to 1.11.2, there are a couple of things you need to be aware of:

ItemStacks are never null §

Starting in 1.11, ItemStacks can never, ever be null. Instead of checking for null-ness, you use the ItemStack.isEmpty method to make sure the stack contains something.

ItemStack private fields §

In 1.11, the ItemStack.stackSize field was made private. Instead of directly modifying this field like before, there are getter, setter, and mutator methods available.

• getCount: equivalent to simply retrieving the field.
• setCount: equivalent to setting the field
• grow: equivalent to increasing the field. stack.grow(1) is equivalent to stack.stackSize++.
• shrink: equivalent to decreasing the field. stack.shrink(1) is equivalent to stack.stackSize--.

Note: The default Forge MDK comes with older MCP mappings in which the new ItemStack methods aren’t named. You’ll need to change the mappings version from snapshot_20161111 to the latest (snapshot_20170330 as of this post).

Resources §

In 1.11.2, Minecraft enforces all resource file names being completely lowercase. This practically enforces snake_case instead of camelCase. You’ll need to rename all your resource files (blockstates, models, textures, etc.) and change all the corresponding uses of their old names in code.

Other §

Aside from those major changes, there are a couple of minor things:

• CreativeTabs.getTabIconItem returns an ItemStack, not an Item now.
• Various mapping changes throughout the MC codebase. You can search on here to see mapping changes in 1.11.2.