Add more missing nullability annotations

Author: rainbowdashlabs

src/main/java/net/dv8tion/jda/api/entities/SKU.java

@@ -16,6 +16,7 @@
 
 package net.dv8tion.jda.api.entities;
 
+import javax.annotation.Nonnull;
 import java.util.Set;
 
 /**
@@ -27,24 +28,28 @@ public interface SKU extends SkuSnowflake
      * Type of the SKU
      * @return SKU type
      */
+    @Nonnull
     SKUType getType();
 
     /**
      * Customer-facing name of your premium offering
      * @return SKU name
      */
+    @Nonnull
     String getName();
 
     /**
      * System-generated URL slug based on the SKU's name
      * @return SKU slug
      */
+    @Nonnull
     String getSlug();
 
     /**
      * Flags can be used to differentiate user and server subscriptions
      * @return set of flags.
      */
+    @Nonnull
     Set<SKUFlag> getFlags();
 
     /**

src/main/java/net/dv8tion/jda/api/entities/SKUType.java

@@ -16,6 +16,8 @@
 
 package net.dv8tion.jda.api.entities;
 
+import javax.annotation.Nonnull;
+
 /**
  * SKU Types represent the type of the offered SKU.
  *
@@ -61,6 +63,7 @@ public enum SKUType
      *
      * @return SKU type or {@link #UNKNOWN} if the SKU is not known.
      */
+    @Nonnull
     public static SKUType fromId(int type)
     {
         for (SKUType value : values())

src/main/java/net/dv8tion/jda/internal/entities/SKUImpl.java

@@ -20,6 +20,7 @@
 import net.dv8tion.jda.api.entities.SKUFlag;
 import net.dv8tion.jda.api.entities.SKUType;
 
+import javax.annotation.Nonnull;
 import java.util.Set;
 
 public class SKUImpl extends SkuSnowflakeImpl implements SKU
@@ -39,24 +40,28 @@ public SKUImpl(long id, SKUType type, String name, String slug, Set<SKUFlag> fla
     }
 
     @Override
+    @Nonnull
     public SKUType getType()
     {
         return type;
     }
 
     @Override
+    @Nonnull
     public String getName()
     {
         return name;
     }
 
     @Override
+    @Nonnull
     public String getSlug()
     {
         return slug;
     }
 
     @Override
+    @Nonnull
     public Set<SKUFlag> getFlags()
     {
         return flags;