if(keys[i] == null){
LeadingValueCompressionProvider.writeByteArray(oos, null, previous, 0);
}else{
out2.reset();
ser.serialize(out3,keys[i]);
byte[] b = out2.toByteArray();
LeadingValueCompressionProvider.writeByteArray(oos, b, previous, 0);
previous = b;
}
}