Add Command#getVersion (#1741)

src/main/java/net/dv8tion/jda/api/interactions/commands/Command.java

@@ -19,9 +19,11 @@
 import net.dv8tion.jda.api.JDA;
 import net.dv8tion.jda.api.entities.Guild;
 import net.dv8tion.jda.api.entities.ISnowflake;
+import net.dv8tion.jda.api.interactions.commands.build.CommandData;
 import net.dv8tion.jda.api.interactions.commands.privileges.CommandPrivilege;
 import net.dv8tion.jda.api.requests.RestAction;
 import net.dv8tion.jda.api.requests.restaction.CommandEditAction;
+import net.dv8tion.jda.api.utils.TimeUtil;
 import net.dv8tion.jda.api.utils.data.DataArray;
 import net.dv8tion.jda.api.utils.data.DataObject;
 import net.dv8tion.jda.api.utils.data.DataType;
@@ -33,6 +35,7 @@
 
 import javax.annotation.CheckReturnValue;
 import javax.annotation.Nonnull;
+import java.time.OffsetDateTime;
 import java.util.*;
 import java.util.function.Function;
 import java.util.function.Predicate;
@@ -58,7 +61,7 @@ public class Command implements ISnowflake
     private final List<Option> options;
     private final List<SubcommandGroup> groups;
     private final List<Subcommand> subcommands;
-    private final long id, guildId, applicationId;
+    private final long id, guildId, applicationId, version;
     private final boolean defaultEnabled;
 
     public Command(JDAImpl api, Guild guild, DataObject json)
@@ -74,6 +77,7 @@ public Command(JDAImpl api, Guild guild, DataObject json)
         this.options = parseOptions(json, OPTION_TEST, Option::new);
         this.groups = parseOptions(json, GROUP_TEST, SubcommandGroup::new);
         this.subcommands = parseOptions(json, SUBCOMMAND_TEST, Subcommand::new);
+        this.version = json.getUnsignedLong("version");
     }
 
     protected static <T> List<T> parseOptions(DataObject json, Predicate<DataObject> test, Function<DataObject, T> transform)
@@ -310,6 +314,33 @@ public String getApplicationId()
         return Long.toUnsignedString(applicationId);
     }
 
+    /**
+     * The version of this command.
+     * <br>This changes when a command is updated through {@link net.dv8tion.jda.api.JDA#upsertCommand(CommandData) upsertCommand}, {@link net.dv8tion.jda.api.JDA#updateCommands() updateCommands}, or {@link net.dv8tion.jda.api.JDA#editCommandById(String) editCommandById}
+     * <br>Useful for checking if command cache is outdated
+     *
+     * @return The version of the command as a snowflake id.
+     *
+     * @see #getTimeModified()
+     */
+    public long getVersion()
+    {
+        return version;
+    }
+
+    /**
+     * The time this command was updated last.
+     *
+     * @return Time this command was updated last.
+     *
+     * @see #getVersion()
+     */
+    @Nonnull
+    public OffsetDateTime getTimeModified()
+    {
+        return TimeUtil.getTimeCreated(getVersion());
+    }
+
     @Override
     public long getIdLong()
     {