The core check of javac's serial lint warning (JDK-4767441) is to verify the presence of a properly declared serialVersionUID field in serializable classes.

There are other useful checks that could be added, including that serial-involved methods are properly declared rather than being overloads which will get ignored by the serialization system. Those methods include:

 private void writeObject(java.io.ObjectOutputStream stream)
     throws IOException;
 private void readObject(java.io.ObjectInputStream stream)
     throws IOException, ClassNotFoundException;
 private void readObjectNoData()
     throws ObjectStreamException

as discussed in java.io.ObjectInputStream and java.io.ObjectOutputStream. In additional, the serialization spec discusses the methods:

ANY-ACCESS-MODIFIER Object writeReplace()
             throws ObjectStreamException;
ANY-ACCESS-MODIFIER Object readResolve()
            throws ObjectStreamException;

Additional methods are defined for Externalization.