Fix VelocityConfigurationAdapter#getKeys()

Author: DerEchtePilz

commandapi-platforms/commandapi-velocity/commandapi-velocity-plugin/src/main/java/dev/jorel/commandapi/config/VelocityConfigurationAdapter.java

@@ -48,11 +48,7 @@ public String[] getComment(String key) {
 
 	@Override
 	public Set<String> getKeys() {
-		Set<String> keys = new HashSet<>();
-		for (Object key : config.childrenMap().keySet()) {
-			keys.add((String) key);
-		}
-		return keys;
+		return new HashSet<>(nestedOptions(config));
 	}
 
 	@Override
@@ -133,4 +129,19 @@ private CommentedConfigurationNode node(String path) {
 		return config.node(path.split("\\."));
 	}
 
+	private Set<String> nestedOptions(ConfigurationNode node) {
+		Set<String> keys = new HashSet<>();
+		for (Object key : node.childrenMap().keySet()) {
+			ConfigurationNode nestedNode = node.childrenMap().get(key);
+			if (nestedNode.childrenMap().isEmpty()) {
+				keys.add((String) key);
+			} else {
+				for (String nestedKey : nestedOptions(nestedNode)) {
+					keys.add(key + "." + nestedKey);
+				}
+			}
+		}
+		return keys;
+	}
+
 }