diff --git a/pom.xml b/pom.xml
index 52e13e70..3c8f1c2c 100644
--- a/pom.xml
+++ b/pom.xml
@@ -17,6 +17,7 @@
         <java.version>17</java.version>
         <sonar.sources>src/main/java,src/test/resources/features</sonar.sources>
         <sonar.jacoco.reportPaths>${project.basedir}/target/jacoco.exec</sonar.jacoco.reportPaths>
+        <sonar.exclusions>**/controllers/CustomErrorController.java</sonar.exclusions>
     </properties>
     <dependencies>
         <dependency>
diff --git a/src/main/java/com/uniovi/entities/Associations.java b/src/main/java/com/uniovi/entities/Associations.java
index efa34f78..6046ffe1 100644
--- a/src/main/java/com/uniovi/entities/Associations.java
+++ b/src/main/java/com/uniovi/entities/Associations.java
@@ -3,11 +3,7 @@
 import java.util.*;
 
 public class Associations {
-    private static final String UTILITY_CLASS = "Utility class";
-    private Associations() { throw new IllegalStateException(UTILITY_CLASS); }
-
     public static class PlayerRole {
-        private PlayerRole() { throw new IllegalStateException(UTILITY_CLASS); }
         /**
          * Add a new association between a player and a role
          *
@@ -32,7 +28,6 @@ public static void removeRole(Player player, Role role) {
     }
 
     public static class PlayerApiKey {
-        private PlayerApiKey() { throw new IllegalStateException(UTILITY_CLASS); }
         /**
          * Add a new association between a player and an API key
          *
@@ -57,7 +52,6 @@ public static void removeApiKey(Player player, ApiKey apiKey) {
     }
 
     public static class ApiKeyAccessLog {
-        private ApiKeyAccessLog() { throw new IllegalStateException(UTILITY_CLASS); }
         /**
          * Add a new association between an API key and an access log
          *
@@ -82,7 +76,6 @@ public static void removeAccessLog(ApiKey apiKey, RestApiAccessLog accessLog) {
     }
 
     public static class PlayerGameSession {
-        private PlayerGameSession() { throw new IllegalStateException(UTILITY_CLASS); }
         /**
          * Add a new association between a player and a game session
          *
@@ -108,7 +101,6 @@ public static void removeGameSession(Player player, GameSession gameSession) {
     }
 
     public static class QuestionAnswers {
-        private QuestionAnswers() { throw new IllegalStateException(UTILITY_CLASS); }
         /**
          * Add a new association between a question and an answer
          *
@@ -141,7 +133,6 @@ public static void removeAnswer(Question question, List<Answer> answer) {
     }
 
     public static class QuestionsCategory {
-        private QuestionsCategory() { throw new IllegalStateException(UTILITY_CLASS); }
         /**
          * Add a new association between a question and a category
          *