private long calculateMemoryUsageRoundedDownToMebibytes() {
        return (Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory()) / (1024 * 1024);
    }
test that the continued creation of proxy classes does not
constantly consume memory.
jgiven-core/src/test/java/com/tngtech/jgiven/impl/ProxyClassPerformanceTest.java