In the file EntitySpear.java

@Override
	protected void readEntityFromNBT(NBTTagCompound p_70037_1_) { }

	@Override
	protected void writeEntityToNBT(NBTTagCompound p_70014_1_) { }

what is p_70037_1_ and where is it defined

Obfuscated naming, also since its in the nbt method the “ p_70037_1_ “ is just the name of the field, you can use it to read/write to nbt (save to the game)

Thanks