@Override
	public boolean equals(final Object obj) {
		return obj instanceof DoubleAdder other &&
			Double.compare(doubleValue(), other.doubleValue()) == 0;
	}
Check if {@code this} and the {@code other} {@code DoubleAdder} maintain
the same internal state.

@param other the other object
@return {@code true} if {@code this} and the {@code other} adder have
        the same state, {@code false otherwise}
jenetics/src/main/java/io/jenetics/internal/math/DoubleAdder.java