Worked on #15326. Added my forgotten HttpServletResponse into the controller method.

src/main/java/de/thm/arsnova/controller/LecturerQuestionController.java

@@ -344,7 +344,8 @@ public class LecturerQuestionController extends AbstractController {
 	@RequestMapping(value = "/{questionId}/thumbs", method = RequestMethod.POST)
 	public ThumbnailResponse getThumbnails(
 			@PathVariable final String questionId,
-			@RequestBody final ThumbnailRequest thumbRequest
+			@RequestBody final ThumbnailRequest thumbRequest,
+			final HttpServletResponse response
 			) {
 		
 		return questionService.getThumbnails(questionId, thumbRequest);
@@ -353,7 +354,8 @@ public class LecturerQuestionController extends AbstractController {
 	@RequestMapping(value = "/{questionId}/answer/{answerId}/image", method = RequestMethod.GET)
 	public String getImage(
 			@PathVariable final String questionId,
-			@PathVariable final String answerId
+			@PathVariable final String answerId,
+			final HttpServletResponse response
 			) {
 		
 		return questionService.getImage(questionId, answerId);

src/main/java/de/thm/arsnova/services/QuestionService.java

@@ -540,6 +540,9 @@ public class QuestionService implements IQuestionService, ApplicationEventPublis
 		}
 
 		Answer theAnswer = answer.generateAnswerEntity(user, question);
+		if ("freetext".equals(theAnswer.getType())) {
+			ImageUtils.generateThumbnailImage(theAnswer);
+		}
 
 		return databaseDao.saveAnswer(theAnswer, user, question, getSession(question.getSessionKeyword()));
 	}
@@ -554,6 +557,9 @@ public class QuestionService implements IQuestionService, ApplicationEventPublis
 		}
 
 		final Question question = getQuestion(answer.getQuestionId());
+		if ("freetext".equals(answer.getType())) {
+			ImageUtils.generateThumbnailImage(answer);
+		}
 		final Answer result = databaseDao.updateAnswer(realAnswer);
 		final Session session = databaseDao.getSessionFromKeyword(question.getSessionKeyword());
 		this.publisher.publishEvent(new NewAnswerEvent(this, session, result, user, question));