If you do

import java.security.SecureRandom;
class JRand {
  public static void main(String args[]) throws Exception {
    System.out.println("Ok: " +
      SecureRandom.getInstance("SHA1PRNG").nextLong());
  }
}

then SecureRandom will read from /dev/random even if securerandom.source is configured to use /dev/urandom. This is a problem if /dev/urandom was chosen because /dev/random is not working properly.

The root cause is that 4705093 assigned special meaning to the string "/dev/urandom".