diff --git a/api/src/main/java/org/geysermc/geyser/api/entity/data/GeyserEntityDataType.java b/api/src/main/java/org/geysermc/geyser/api/entity/data/GeyserEntityDataType.java
index 3484f217b..c1c2e79d1 100644
--- a/api/src/main/java/org/geysermc/geyser/api/entity/data/GeyserEntityDataType.java
+++ b/api/src/main/java/org/geysermc/geyser/api/entity/data/GeyserEntityDataType.java
@@ -25,6 +25,7 @@
 
 package org.geysermc.geyser.api.entity.data;
 
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.geysermc.geyser.api.GeyserApi;
 import org.geysermc.geyser.api.entity.type.GeyserEntity;
 
@@ -46,7 +47,7 @@ public interface GeyserEntityDataType<T> {
      *
      * @return the class of the value used by this entity data type
      */
-    Class<T> typeClass();
+    @NonNull Class<T> typeClass();
 
     /**
      * Gets the unique name of this data type.
@@ -56,12 +57,12 @@ public interface GeyserEntityDataType<T> {
      *
      * @return the name of this entity data type
      */
-    String name();
+    @NonNull String name();
 
     /**
      * For API usage only; use the types defined in {@link GeyserEntityDataTypes}
      */
-    static <T> GeyserEntityDataType<T> of(Class<T> typeClass, String name) {
+    static <T> GeyserEntityDataType<T> of(@NonNull Class<T> typeClass, @NonNull String name) {
         return GeyserApi.api().provider(GeyserEntityDataType.class, typeClass, name);
     }
 }
diff --git a/api/src/main/java/org/geysermc/geyser/api/entity/data/GeyserListEntityDataType.java b/api/src/main/java/org/geysermc/geyser/api/entity/data/GeyserListEntityDataType.java
index 655a87760..3cb948f01 100644
--- a/api/src/main/java/org/geysermc/geyser/api/entity/data/GeyserListEntityDataType.java
+++ b/api/src/main/java/org/geysermc/geyser/api/entity/data/GeyserListEntityDataType.java
@@ -25,24 +25,28 @@
 
 package org.geysermc.geyser.api.entity.data;
 
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.geysermc.geyser.api.GeyserApi;
 
 import java.util.List;
 
 /**
- * Represents a list of objects for an entity data types
- * For example, there can be multiple hitboxes on an entity
+ * Represents a list of objects for specific entity data types.
+ * For example, there can be multiple hitboxes on an entity.
  *
- * @param <T>
+ * @param <T> the object type in the list
  */
 public interface GeyserListEntityDataType<T> extends GeyserEntityDataType<List<T>> {
 
-    Class<T> listTypeClass();
+    /**
+     * @return the class of the list entries
+     */
+    @NonNull Class<T> listEntryClass();
 
     /**
      * API usage only, use the types defined in {@link GeyserEntityDataTypes}
      */
-    static <T> GeyserListEntityDataType<T> of(Class<T> typeClass, String name) {
+    static <T> GeyserListEntityDataType<T> of(@NonNull Class<T> typeClass, @NonNull String name) {
         return GeyserApi.api().provider(GeyserListEntityDataType.class, List.class, typeClass, name);
     }
 }
diff --git a/api/src/main/java/org/geysermc/geyser/api/entity/data/types/Hitbox.java b/api/src/main/java/org/geysermc/geyser/api/entity/data/types/Hitbox.java
index 46d284512..f7949eb97 100644
--- a/api/src/main/java/org/geysermc/geyser/api/entity/data/types/Hitbox.java
+++ b/api/src/main/java/org/geysermc/geyser/api/entity/data/types/Hitbox.java
@@ -25,6 +25,7 @@
 
 package org.geysermc.geyser.api.entity.data.types;
 
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.cloudburstmc.math.vector.Vector3f;
 import org.geysermc.geyser.api.GeyserApi;
 
@@ -47,7 +48,7 @@ public interface Hitbox {
 
     /**
      * The pivot of the hitbox
-     * @return
+     * @return the pivot
      */
     Vector3f pivot();
 
@@ -60,12 +61,33 @@ public interface Hitbox {
      */
     interface Builder {
 
-        Builder min(Vector3f min);
+        /**
+         * Sets the min corner of the hitbox
+         * @param min the vector of the corner
+         * @return this builder
+         */
+        Builder min(@NonNull Vector3f min);
 
-        Builder max(Vector3f max);
+        /**
+         * Sets the max corner of the hitbox
+         * @param max the vector of the corner
+         * @return this builder
+         */
+        Builder max(@NonNull Vector3f max);
 
-        Builder origin(Vector3f pivot);
+        /**
+         * Sets the pivot of the hitbox
+         * @param pivot the pivot vector
+         * @return this builder
+         */
+        Builder pivot(@NonNull Vector3f pivot);
 
+        /**
+         * Builds this hitbox, defaulting to {@code Vector3f.ZERO} if
+         * any one vector was not provided.
+         *
+         * @return a new hitbox
+         */
         Hitbox build();
     }
 }
diff --git a/core/src/main/java/org/geysermc/geyser/impl/entity/GeyserEntityDataImpl.java b/core/src/main/java/org/geysermc/geyser/impl/entity/GeyserEntityDataImpl.java
index a7c4ec075..e2e12e3fd 100644
--- a/core/src/main/java/org/geysermc/geyser/impl/entity/GeyserEntityDataImpl.java
+++ b/core/src/main/java/org/geysermc/geyser/impl/entity/GeyserEntityDataImpl.java
@@ -27,6 +27,7 @@ package org.geysermc.geyser.impl.entity;
 
 import it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap;
 import lombok.AllArgsConstructor;
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.cloudburstmc.protocol.bedrock.data.entity.EntityDataType;
 import org.cloudburstmc.protocol.bedrock.data.entity.EntityDataTypes;
 import org.cloudburstmc.protocol.bedrock.data.entity.EntityFlag;
@@ -97,12 +98,12 @@ public class GeyserEntityDataImpl<T> implements GeyserEntityDataType<T> {
     }
 
     @Override
-    public Class<T> typeClass() {
+    public @NonNull Class<T> typeClass() {
         return typeClass;
     }
 
     @Override
-    public String name() {
+    public @NonNull String name() {
         return name;
     }
 
diff --git a/core/src/main/java/org/geysermc/geyser/impl/entity/GeyserListEntityDataImpl.java b/core/src/main/java/org/geysermc/geyser/impl/entity/GeyserListEntityDataImpl.java
index bb11baf64..0594a3aab 100644
--- a/core/src/main/java/org/geysermc/geyser/impl/entity/GeyserListEntityDataImpl.java
+++ b/core/src/main/java/org/geysermc/geyser/impl/entity/GeyserListEntityDataImpl.java
@@ -26,6 +26,7 @@
 package org.geysermc.geyser.impl.entity;
 
 import it.unimi.dsi.fastutil.objects.Object2ObjectOpenHashMap;
+import org.checkerframework.checker.nullness.qual.NonNull;
 import org.cloudburstmc.nbt.NbtMap;
 import org.cloudburstmc.protocol.bedrock.data.entity.EntityDataTypes;
 import org.geysermc.geyser.api.entity.data.GeyserListEntityDataType;
@@ -57,7 +58,7 @@ public class GeyserListEntityDataImpl<ListType> extends GeyserEntityDataImpl<Lis
     }
 
     @Override
-    public Class<ListType> listTypeClass() {
+    public @NonNull Class<ListType> listEntryClass() {
         return listTypeClass;
     }
 
@@ -74,7 +75,7 @@ public class GeyserListEntityDataImpl<ListType> extends GeyserEntityDataImpl<Lis
         if (type == null) {
             throw new IllegalArgumentException("Unknown entity data type: " + name);
         }
-        if (type.listTypeClass() == listTypeClass) {
+        if (type.listEntryClass() == listTypeClass) {
             return TYPES.get(name);
         }
         throw new IllegalArgumentException("Unknown entity data type: " + name);
diff --git a/core/src/main/java/org/geysermc/geyser/impl/entity/HitboxImpl.java b/core/src/main/java/org/geysermc/geyser/impl/entity/HitboxImpl.java
index 0e7fd7b8f..1bcf22973 100644
--- a/core/src/main/java/org/geysermc/geyser/impl/entity/HitboxImpl.java
+++ b/core/src/main/java/org/geysermc/geyser/impl/entity/HitboxImpl.java
@@ -102,7 +102,7 @@ public record HitboxImpl(
         }
 
         @Override
-        public Hitbox.Builder origin(Vector3f pivot) {
+        public Hitbox.Builder pivot(Vector3f pivot) {
             Objects.requireNonNull(pivot, "pivot");
             this.pivot = pivot;
             return this;