https://twitter.com/aumasson/status/229947172454551552

JPACollision.java

public class JPACollision {
    public static void main(String[] args) {
        byte[] bytes1 = new byte[] {
            0x58, (byte) 0xa1, (byte) 0x82, 0x6c, 0x00, 0x00, (byte) 0xb1, 0x3b
        };
        byte[] bytes2 = new byte[] {
            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
        };
        byte[] bytes12 = concat(bytes1, bytes2);
        byte[] bytes21 = concat(bytes2, bytes1);
        byte[] bytes11 = concat(bytes1, bytes1);
        byte[] bytes22 = concat(bytes2, bytes2);
        System.out.println(sun.misc.Hashing.murmur3_32(bytes12));
        System.out.println(sun.misc.Hashing.murmur3_32(bytes21));
        System.out.println(sun.misc.Hashing.murmur3_32(bytes11));
        System.out.println(sun.misc.Hashing.murmur3_32(bytes22));
    }

    private static byte[] concat(byte[] bytes1, byte[] bytes2) {
        byte[] result = new byte[bytes1.length + bytes2.length];
        System.arraycopy(bytes1, 0, result, 0, bytes1.length);
        System.arraycopy(bytes2, 0, result, bytes1.length, bytes2.length);
        return result;
    }
}

You need to obtain OpenJDK 7u6 pre release build. The sun.misc.Hashing.murmur3_32 is used via sun.misc.Hashing.stringHash32, that is the hash32(String) in standard Java Hash collections from Java 7u6.