Rolling Average improvements
On new RollingAverage(-1) it throws a NegativeArraySizeException. An IllegalArgumentException with a proper message would be better here since clients should not know that you are using arrays in the implementation.
On new RollingAverageImpl(1).getAverage() it throws an ArithmeticExpression. What about an IllegalStateException here?
If you are using Integer.MIN_VALUE as a special marker value the addData method should not accept it. Just throw an IllegalArgumentException. (I'd consider using Double.NaN here as a named constant, like EMPTY_DATA or just EMPTY.)
Comparing doubles with integers (like point == Integer.MIN_VALUE) might not be precise. See: Why not use Double or Float to represent currency?
If you calculate the new average after every addData call maybe you should cache it and use the cached value in the  getAverageDouble method.
Actually, I'd cache the sum too, and in the addData subtract the old value from the sum (if the array is full) and add the newData to it, then divide it by the number of elements. Maybe there are better algorithms.