code: public static void setPRNGProvider(String prngName, String packageName) {
             VersionFourGenerator.usePRNG = prngName;
             VersionFourGenerator.usePRNGPackage = packageName;
             VersionFourGenerator.secureRandom = null;
         }
docs: <p>Allows clients to set the pseudo-random number generator implementation used when generating a version four uuid with
  the secure option. The secure option uses a <code>SecureRandom</code>. The packageName string may be null to specify
  no preferred package.</p>
  
  @param prngName the pseudo-random number generator implementation name. For example "SHA1PRNG".
  @param packageName the package name for the PRNG provider. For example "SUN".