diff --git a/src/main/java/de/thm/arsnova/controller/ConfigurationController.java b/src/main/java/de/thm/arsnova/controller/ConfigurationController.java
index 134eda8b4852996d10aad1a0a9ae1f21223c5328..8956c1ea0fee77e93e40840d1658cdac7f5f26b6 100644
--- a/src/main/java/de/thm/arsnova/controller/ConfigurationController.java
+++ b/src/main/java/de/thm/arsnova/controller/ConfigurationController.java
@@ -27,6 +27,7 @@ import org.springframework.web.bind.annotation.ResponseBody;
 
 import javax.servlet.http.HttpServletRequest;
 import java.util.HashMap;
+import java.util.Map;
 
 /**
  * The ConfigurationController provides frontend clients with information necessary to correctly interact with the
@@ -161,11 +162,11 @@ public class ConfigurationController extends AbstractController {
 
 	@RequestMapping(method = RequestMethod.GET)
 	@ResponseBody
-	public HashMap<String, Object> getConfiguration(HttpServletRequest request) {
-		HashMap<String, Object> config = new HashMap<>();
-		HashMap<String, Boolean> features = new HashMap<>();
-		HashMap<String, String> publicPool = new HashMap<>();
-		HashMap<String, Object> splashscreen = new HashMap<>();
+	public Map<String, Object> getConfiguration(HttpServletRequest request) {
+		Map<String, Object> config = new HashMap<>();
+		Map<String, Boolean> features = new HashMap<>();
+		Map<String, String> publicPool = new HashMap<>();
+		Map<String, Object> splashscreen = new HashMap<>();
 
 		/* The API path could be unknown to the client in case the request was forwarded */
 		if ("".equals(apiPath)) {
@@ -268,7 +269,7 @@ public class ConfigurationController extends AbstractController {
 		}
 
 		if (!"".equals(trackingTrackerUrl)) {
-			HashMap<String, String> tracking = new HashMap<>();
+			Map<String, String> tracking = new HashMap<>();
 			config.put("tracking", tracking);
 
 			tracking.put("provider", trackingProvider);
diff --git a/src/main/java/de/thm/arsnova/events/LockVoteEvent.java b/src/main/java/de/thm/arsnova/events/LockVoteEvent.java
index a3831c9983cede362aa9efe5ed0c3cb99d8c4aba..b33922f4f25bdc75a5df1a520fffce1e14c0b548 100644
--- a/src/main/java/de/thm/arsnova/events/LockVoteEvent.java
+++ b/src/main/java/de/thm/arsnova/events/LockVoteEvent.java
@@ -21,6 +21,7 @@ import de.thm.arsnova.entities.Question;
 import de.thm.arsnova.entities.Session;
 
 import java.util.HashMap;
+import java.util.Map;
 
 /**
  * Fires whenever voting on a question is disabled.
@@ -48,8 +49,8 @@ public class LockVoteEvent extends SessionEvent {
 		return this.question.isVotingDisabled();
 	}
 
-	public HashMap<String, Object> getVotingAdmission() {
-		HashMap<String, Object> map = new HashMap<>();
+	public Map<String, Object> getVotingAdmission() {
+		Map<String, Object> map = new HashMap<>();
 
 		map.put("_id", getQuestionId());
 		map.put("variant", getQuestionVariant());
diff --git a/src/main/java/de/thm/arsnova/events/PiRoundDelayedStartEvent.java b/src/main/java/de/thm/arsnova/events/PiRoundDelayedStartEvent.java
index 6b3418d9addc6034b6d6f220621c68cb295856ce..6fdc587e38791ae1c56c54e2fa329841dd93b9f2 100644
--- a/src/main/java/de/thm/arsnova/events/PiRoundDelayedStartEvent.java
+++ b/src/main/java/de/thm/arsnova/events/PiRoundDelayedStartEvent.java
@@ -21,6 +21,7 @@ import de.thm.arsnova.entities.Question;
 import de.thm.arsnova.entities.Session;
 
 import java.util.HashMap;
+import java.util.Map;
 
 /**
  * Fires whenever a delayed peer instruction round is initiated. The delayed part denotes that this round might not
@@ -69,8 +70,8 @@ public class PiRoundDelayedStartEvent extends SessionEvent {
 		return piRound;
 	}
 
-	public HashMap<String, Object> getPiRoundInformations() {
-		HashMap<String, Object> map = new HashMap<>();
+	public Map<String, Object> getPiRoundInformations() {
+		Map<String, Object> map = new HashMap<>();
 
 		map.put("_id", getQuestionId());
 		map.put("endTime", getEndTime());
diff --git a/src/main/java/de/thm/arsnova/events/PiRoundEndEvent.java b/src/main/java/de/thm/arsnova/events/PiRoundEndEvent.java
index 0d1d5df8374d86cb71e420d7293449eb3575eaf2..b87d12590bdd7e3667d7998367b86cbb4514b07d 100644
--- a/src/main/java/de/thm/arsnova/events/PiRoundEndEvent.java
+++ b/src/main/java/de/thm/arsnova/events/PiRoundEndEvent.java
@@ -21,6 +21,7 @@ import de.thm.arsnova.entities.Question;
 import de.thm.arsnova.entities.Session;
 
 import java.util.HashMap;
+import java.util.Map;
 
 /**
  * Fires whenever a peer instruction round has ended.
@@ -51,8 +52,8 @@ public class PiRoundEndEvent extends SessionEvent {
 		return questionVariant;
 	}
 
-	public HashMap<String, String> getPiRoundEndInformations() {
-		HashMap<String, String> map = new HashMap<>();
+	public Map<String, String> getPiRoundEndInformations() {
+		Map<String, String> map = new HashMap<>();
 
 		map.put("_id", getQuestionId());
 		map.put("variant", getQuestionVariant());
diff --git a/src/main/java/de/thm/arsnova/events/PiRoundResetEvent.java b/src/main/java/de/thm/arsnova/events/PiRoundResetEvent.java
index 92a7095fc2279f1dedddbd5360ef281b15709a08..429aeb274c1b26fecbc1f779734316a9d2835ca1 100644
--- a/src/main/java/de/thm/arsnova/events/PiRoundResetEvent.java
+++ b/src/main/java/de/thm/arsnova/events/PiRoundResetEvent.java
@@ -21,6 +21,7 @@ import de.thm.arsnova.entities.Question;
 import de.thm.arsnova.entities.Session;
 
 import java.util.HashMap;
+import java.util.Map;
 
 /**
  * Fires whenever a peer instruction round is reset.
@@ -51,8 +52,8 @@ public class PiRoundResetEvent extends SessionEvent {
 		return questionVariant;
 	}
 
-	public HashMap<String, String> getPiRoundResetInformations() {
-		HashMap<String, String> map = new HashMap<>();
+	public Map<String, String> getPiRoundResetInformations() {
+		Map<String, String> map = new HashMap<>();
 
 		map.put("_id", getQuestionId());
 		map.put("variant", getQuestionVariant());
diff --git a/src/main/java/de/thm/arsnova/events/UnlockVoteEvent.java b/src/main/java/de/thm/arsnova/events/UnlockVoteEvent.java
index ef3bf8c7b279966a2157ea05de3dc1d8c01d9040..69a1f45717e077339a28267700a43a8e6123703a 100644
--- a/src/main/java/de/thm/arsnova/events/UnlockVoteEvent.java
+++ b/src/main/java/de/thm/arsnova/events/UnlockVoteEvent.java
@@ -21,6 +21,7 @@ import de.thm.arsnova.entities.Question;
 import de.thm.arsnova.entities.Session;
 
 import java.util.HashMap;
+import java.util.Map;
 
 /**
  * Fires whenever voting on a question is enabled.
@@ -48,8 +49,8 @@ public class UnlockVoteEvent extends SessionEvent {
 		return this.question.isVotingDisabled();
 	}
 
-	public HashMap<String, Object> getVotingAdmission() {
-		HashMap<String, Object> map = new HashMap<>();
+	public Map<String, Object> getVotingAdmission() {
+		Map<String, Object> map = new HashMap<>();
 
 		map.put("_id", getQuestionId());
 		map.put("variant", getQuestionVariant());