Fix terrain API repo failing if no cache was provided

api/src/main/java/com/seibel/distanthorizons/api/interfaces/data/IDhApiTerrainDataCache.java

@@ -9,12 +9,15 @@ package com.seibel.distanthorizons.api.interfaces.data;
  * @version 2024-7-14
  * @since API 3.0.0
  */
-public interface IDhApiTerrainDataCache
+public interface IDhApiTerrainDataCache // TODO should this be AutoClosable?
 {
 	/**
 	 * Removes any data that's currently stored in this cache.
 	 * This cane be done to free up memory or invalidate 
 	 * the cache so fresh data can be pulled in.
+	 * <br><br>
+	 * This should be called before de-referencing this object
+	 * so DH can handle any necessary cleanup for internal objects.
 	 */
 	void clear();