code: public static String unmarshallString(ObjectInput in) throws IOException {
        if (in.readBoolean()) {
           return null;
        }
        return in.readUTF();
     }
docs: Unmarshall a {@link String}.
  
  @param in {@link ObjectInput} to read.
  @return The {@link String} or {@code null}.
  @throws IOException If any of the usual Input/Output related exceptions occur.
  @see #marshallString(String, ObjectOutput).