public static void checkNotNegative(long value, String argName) {
    checkArgument(value >= 0, "'%s' must not be negative.", argName);
  }
@Test
  public void testCheckNotNegative() throws Exception {
    int positiveArg = 1;
    int zero = 0;
    int negativeArg = -1;

    // Should not throw.
    Validate.checkNotNegative(zero, "zeroArg");
    Validate.checkNotNegative(positiveArg, "positiveArg");

    // Verify it throws.

    intercept(IllegalArgumentException.class,
        "'negativeArg' must not be negative",
        () -> Validate.checkNotNegative(negativeArg, "negativeArg"));

  }