Because 0 is an integer constant, -0 is an integer, too. Integers have no
concept of “negative zero,” so it is the same as plain 0.
The value is then widened to a floating-point number. And while floating-point
numbers have a concept of “negative zero,” the integral 0 is widened to the
floating-point “positive” zero.
To write a negative zero, you have to write a constant that is a floating-point
number. One simple way to do that is to write -0.0.
Suppress false positives by adding the suppression annotation @SuppressWarnings("AttemptedNegativeZero") to the enclosing element.