default long preHeat() {
        List<TestCase> testCases = internalGetTestCasesForPreheat();
        return preHeat(testCases, testCases.size(), true);
    }
Runs all testcases once to heat up the JVM.
@return Number of actually done testcases.
analyzer/src/main/java/nl/basjes/parse/useragent/AnalyzerPreHeater.java