plugins types FEATURE resolved schema prefix format

Must be used for default values of unions
with leafrefs - on repeated validation
the parsed module would be always required.
Also, support for resolving empty prefixes
(get local module) except for JSON.
diff --git a/src/tree_data.h b/src/tree_data.h
index a7512f2..6e39f69 100644
--- a/src/tree_data.h
+++ b/src/tree_data.h
@@ -137,6 +137,7 @@
  */
 typedef enum {
     LY_PREF_SCHEMA,          /**< value prefixes map to YANG import prefixes */
+    LY_PREF_SCHEMA_RESOLVED, /**< value prefixes map to module structures directly */
     LY_PREF_XML,             /**< value prefixes map to XML namespace prefixes */
     LY_PREF_JSON             /**< value prefixes map to module names */
 } LY_PREFIX_FORMAT;
@@ -222,6 +223,15 @@
 };
 
 /**
+ * @brief Prefix data pair mapping of prefixes to modules. In case the format is ::LY_PREF_SCHEMA_RESOLVED,
+ * the expected prefix data is a sized array of these structures.
+ */
+struct lyd_value_prefix {
+    char *prefix;                   /**< used prefix */
+    const struct lys_module *mod;   /**< mapping to a module */
+};
+
+/**
  * @brief Metadata structure.
  *
  * The structure provides information about metadata of a data element. Such attributes must map to