public static void assertThat(final AtomicBoolean pass,
                                      final StringBuilder failures,
                                      final String message,
                                      final boolean passed) {
            if (!passed) {
                if (failures != null) {
                    failures.append("\n").append(message);
                }
                pass.set(false);
            }
        }
Generates a keySpace number of unique keys normally distributed,
with the mean at 0 and stdDev 1/3 of the way through the keySpace
any sample more than 3 standard deviations from the mean are assigned to the 0 key.
<p>
This is designed to roughly balance the key properties of two dominant real-world
data distribution: Zipfian and Normal, while also being efficient to generate.
streams/src/test/java/org/apache/kafka/streams/tests/RelationalSmokeTest.java