code: @Override
      public Number getNumber(int index) {
          synchronized (lock) {
              return CBLConverter.asNumber(getMValue(internalArray, index).asNative(internalArray));
          }
      }
docs: Gets value at the given index as a Number. Returns null if the value doesn't exist, or its value is not a Number.
  
  @param index the index. This value must not exceed the bounds of the array.
  @return the Number or nil.