public JsonElement serialize(AnswerPlaceholder src, Type typeOfSrc, JsonSerializationContext context) {
final List<String> hints = src.getHints();
final int length = src.getLength();
final int start = src.getOffset();
final String possibleAnswer = src.getPossibleAnswer();
<BUG>int line = -1;</BUG>
final Gson gson = new GsonBuilder().setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES).create();
final JsonObject answerPlaceholder = new JsonObject();
<BUG>answerPlaceholder.addProperty(LINE, line);
answerPlaceholder.addProperty(START, start);
</BUG>
answerPlaceholder.addProperty(LENGTH, length);

public JsonElement serialize(AnswerPlaceholder src, Type typeOfSrc, JsonSerializationContext context) {
final List<String> hints = src.getHints();
final int length = src.getLength();
final int start = src.getOffset();
final String possibleAnswer = src.getPossibleAnswer();
final Gson gson = new GsonBuilder().setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES).create();
final JsonObject answerPlaceholder = new JsonObject();
answerPlaceholder.addProperty(OFFSET, start);
answerPlaceholder.addProperty(LENGTH, length);
