Add methods to check if all users or members are cached

javacord-api/src/main/java/org/javacord/api/DiscordApi.java

@@ -577,6 +577,15 @@ default CompletableFuture<Void> updateAvatar(InputStream avatar, String fileType
      */
     boolean isUserCacheEnabled();
 
+    /**
+     * Checks if all users of available servers are in the cache.
+     *
+     * @return Whether or not all users of available servers are in the cache.
+     */
+    default boolean hasAllUsersInCache() {
+        return !getServers().stream().anyMatch(Server::hasAllMembersInCache);
+    }
+
     /**
      * Gets a collection with all currently cached users.
      *

javacord-api/src/main/java/org/javacord/api/entity/server/Server.java

@@ -427,6 +427,13 @@ default CompletableFuture<Integer> pruneMembers(int days) {
      */
     CompletableFuture<Collection<RichInvite>> getInvites();
 
+    /**
+     * Checks if all members of the server are in the cache.
+     *
+     * @return Whether or not all members of the server are in the cache.
+     */
+    boolean hasAllMembersInCache();
+
     /**
      * Gets a collection with all members of the server.
      *

javacord-core/src/main/java/org/javacord/core/entity/server/ServerImpl.java

@@ -1216,6 +1216,11 @@ public CompletableFuture<Collection<RichInvite>> getInvites() {
                 });
     }
 
+    @Override
+    public boolean hasAllMembersInCache() {
+        return getRealMembers().size() >= getMemberCount();
+    }
+
     @Override
     public Set<User> getMembers() {
         return api.getEntityCache().get().getMemberCache()