cannot find symbol error

I'm trying to make a log block that is rotatable. I followed a few tutorials to the letter, but it always fails. Every time I try to compile I get the following error:
 

C:\Pylo\MCreator181\forge\build\sources\main\java\mod\mcreator\mcreator_decayLog.java:261: error: cannot find symbol
			return new BlockStateContainer(this, new IProperty[]{FACING});
			                                         ^
  symbol:   class IProperty
  location: class BlockCustom
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
1 error

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':compileJava'.
> Compilation failed; see the compiler error output for details.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

I've made sure to import BlockStateContainer, as well as BlockHorizontal, but it just won't work. Using version 1.8.1