@Test
    void all_zeros_checks_length_and_array_contents() {
        assertTrue(SideChannelSafe.allZeros(new byte[0]));
        assertFalse(SideChannelSafe.allZeros(new byte[]{ 1 }));
        assertTrue(SideChannelSafe.allZeros(new byte[]{ 0 }));
        assertFalse(SideChannelSafe.allZeros(new byte[]{ 0, 0, 127, 0 }));
        assertFalse(SideChannelSafe.allZeros(new byte[]{ 0, 0, -1, 0 }));
        assertTrue(SideChannelSafe.allZeros(new byte[]{ 0, 0, 0 }));
    }
_Functional_ test of side channel safe utility functions. Testing that they're actually
(probably) side channel safe would be too flaky since it's inherently timing-dependent.
security-utils/src/test/java/com/yahoo/security/SideChannelSafeTest.java