NMS: NoSuchMethodException

Hello, all, I am fairly new to reflection, and NMS itself. So I followed some tutorials that were a bit old from a minecraft version or two that hasn't been updated. I was looking into the one by Ivan about Custom Path Tiles. I noticed I was getting this NoSuchMethodException, and so I went to see how I could fix it. So in his code, he is grabbing the private field 'a' from the class PathfindingGoalSelector. The fields follow (v1_5_R2):

Code:

private List a = new UnsafeList();
private List b = new UnsafeList();
private final MethodProfiler c;
private int d = 0;
private int e = 3;

Once again, he was accessing the field 'a'.

Then when we look into the newest version (v1_7_R1) here are the fields:

Code:

private static final Logger a = LogManager.getLogger();
 
private List b = new UnsafeList();
private List c = new UnsafeList();
private final MethodProfiler d;
private int e;
private int f = 3;

So now that first List is now named 'b', so I switched the 'a' out for a 'b', but I still get that exception. Is this because the field is private? If that's not the problem, what what is it?