public boolean isZero() {
        return value.compareTo(BigDecimal.ZERO) == 0;
    }
@Test
    void testIsZero() {
        final Resource resource1 = new TestResource(0.0);
        final Resource resource2 = new TestResource(1.0);

        assertThat(resource1.isZero()).isTrue();
        assertThat(resource2.isZero()).isFalse();
    }