diff --git a/api/src/main/java/me/lucko/luckperms/api/Track.java b/api/src/main/java/me/lucko/luckperms/api/Track.java
index be92aafcb..a36092893 100644
--- a/api/src/main/java/me/lucko/luckperms/api/Track.java
+++ b/api/src/main/java/me/lucko/luckperms/api/Track.java
@@ -120,6 +120,7 @@ public interface Track {
      * @throws NullPointerException      if the group is null
      * @throws IllegalStateException     if the group instance was not obtained from LuckPerms.
      */
+    @Nonnull
     DataMutateResult appendGroup(@Nonnull Group group);
 
     /**
@@ -132,6 +133,7 @@ public interface Track {
      * @throws NullPointerException      if the group is null
      * @throws IllegalStateException     if the group instance was not obtained from LuckPerms.
      */
+    @Nonnull
     DataMutateResult insertGroup(@Nonnull Group group, int position) throws IndexOutOfBoundsException;
 
     /**
@@ -142,6 +144,7 @@ public interface Track {
      * @throws NullPointerException  if the group is null
      * @throws IllegalStateException if the group instance was not obtained from LuckPerms.
      */
+    @Nonnull
     DataMutateResult removeGroup(@Nonnull Group group);
 
     /**
@@ -151,6 +154,7 @@ public interface Track {
      * @return the result of the operation
      * @throws NullPointerException if the group is null
      */
+    @Nonnull
     DataMutateResult removeGroup(@Nonnull String group);
 
     /**
diff --git a/api/src/main/java/me/lucko/luckperms/api/User.java b/api/src/main/java/me/lucko/luckperms/api/User.java
index 4c0bb4d49..0420a7e75 100644
--- a/api/src/main/java/me/lucko/luckperms/api/User.java
+++ b/api/src/main/java/me/lucko/luckperms/api/User.java
@@ -74,6 +74,7 @@ public interface User extends PermissionHolder {
      * @throws IllegalStateException     if the user is not a member of that group
      * @throws NullPointerException      if the group is null
      */
+    @Nonnull
     DataMutateResult setPrimaryGroup(@Nonnull String group);
 
     /**
diff --git a/common/src/main/java/me/lucko/luckperms/common/api/delegates/model/ApiTrack.java b/common/src/main/java/me/lucko/luckperms/common/api/delegates/model/ApiTrack.java
index 0e49a17cb..98371fd78 100644
--- a/common/src/main/java/me/lucko/luckperms/common/api/delegates/model/ApiTrack.java
+++ b/common/src/main/java/me/lucko/luckperms/common/api/delegates/model/ApiTrack.java
@@ -107,24 +107,28 @@ public final class ApiTrack implements me.lucko.luckperms.api.Track {
         return this.handle.demote(ApiUser.cast(user), contextSet, Predicates.alwaysTrue(), null);
     }
 
+    @Nonnull
     @Override
     public DataMutateResult appendGroup(@Nonnull Group group) {
         Objects.requireNonNull(group, "group");
         return this.handle.appendGroup(ApiGroup.cast(group));
     }
 
+    @Nonnull
     @Override
     public DataMutateResult insertGroup(@Nonnull Group group, int position) throws IndexOutOfBoundsException {
         Objects.requireNonNull(group, "group");
         return this.handle.insertGroup(ApiGroup.cast(group), position);
     }
 
+    @Nonnull
     @Override
     public DataMutateResult removeGroup(@Nonnull Group group) {
         Objects.requireNonNull(group, "group");
         return this.handle.removeGroup(ApiGroup.cast(group));
     }
 
+    @Nonnull
     @Override
     public DataMutateResult removeGroup(@Nonnull String group) {
         Objects.requireNonNull(group, "group");
diff --git a/common/src/main/java/me/lucko/luckperms/common/api/delegates/model/ApiUser.java b/common/src/main/java/me/lucko/luckperms/common/api/delegates/model/ApiUser.java
index 4ddd992d2..504d84a08 100644
--- a/common/src/main/java/me/lucko/luckperms/common/api/delegates/model/ApiUser.java
+++ b/common/src/main/java/me/lucko/luckperms/common/api/delegates/model/ApiUser.java
@@ -72,6 +72,7 @@ public final class ApiUser extends ApiPermissionHolder implements me.lucko.luckp
         return this.handle.getPrimaryGroup().getValue();
     }
 
+    @Nonnull
     @Override
     public DataMutateResult setPrimaryGroup(@Nonnull String group) {
         Objects.requireNonNull(group, "group");