private void definePackageIfNecessary(String className, Class<?> clazz) {
        String packageName = toPackageName(className);
        if (packageName != null && getDefinedPackage(packageName) == null) {
            definePackage(packageName, null, null, null, null, null, null, null);
        }
    }
Names of resources that could not be found. Used to avoid repeated
lookup of commonly accessed, but often not present, resources like
<code>META-INF/services/javax.xml.parsers.SAXParserFactory</code>.
tika-core/src/main/java/org/apache/tika/fork/ClassLoaderProxy.java