Haha no they are not, because I followed instructions from theMchewy from youtube. He said we had to make a structure like this : src\main\java\assets\modid\textures\items
So I did that. It works while testing.
I have made my mod, made additional textures, but my assets aren't in my .jar file after I issue
I have both the "assets" and its subfolders included in my build path.