diff --git a/src/oatpp/core/data/mapping/type/Type.cpp b/src/oatpp/core/data/mapping/type/Type.cpp
index ba13c167..6b16929c 100644
--- a/src/oatpp/core/data/mapping/type/Type.cpp
+++ b/src/oatpp/core/data/mapping/type/Type.cpp
@@ -43,9 +43,8 @@ namespace __class {
 
 std::atomic_int ClassId::ID_COUNTER(0);
 
-ClassId::ClassId(const char* pName, const char* pQualifier)
+ClassId::ClassId(const char* pName)
   : name(pName)
-  , qualifier(pQualifier)
   , id(ID_COUNTER ++)
 {}
 
diff --git a/src/oatpp/core/data/mapping/type/Type.hpp b/src/oatpp/core/data/mapping/type/Type.hpp
index 2a711fa0..db0e2990 100644
--- a/src/oatpp/core/data/mapping/type/Type.hpp
+++ b/src/oatpp/core/data/mapping/type/Type.hpp
@@ -35,15 +35,35 @@ namespace oatpp { namespace data { namespace mapping { namespace type {
   
 class Type; // FWD
 
+/**
+ * Structure representing `ID` of the type class.
+ */
 class ClassId {
 private:
   static std::atomic_int ID_COUNTER;
 public:
+  /**
+   * Get count of all type classes created.
+   * @return
+   */
   static int getClassCount();
 public:
-  ClassId(const char* pName, const char* pQualifier = nullptr);
+
+  /**
+   * Constructor.
+   * @param pName
+   */
+  ClassId(const char* pName);
+
+  /**
+   * Name of the type class.
+   */
   const char* const name;
-  const char* const qualifier;
+
+  /**
+   * Integer ID of the type class. <br>
+   * *Note: class type IDs are integer values incremented continuously from [0 to `getClassCount()`]*
+   */
   const v_int32 id;
 };
 
diff --git a/src/oatpp/parser/json/mapping/Deserializer.hpp b/src/oatpp/parser/json/mapping/Deserializer.hpp
index 643b1446..b873f3d0 100644
--- a/src/oatpp/parser/json/mapping/Deserializer.hpp
+++ b/src/oatpp/parser/json/mapping/Deserializer.hpp
@@ -179,12 +179,31 @@ private:
   std::vector<DeserializerMethod> m_methods;
 public:
 
+  /**
+   * Constructor.
+   * @param config
+   */
   Deserializer(const std::shared_ptr<Config>& config = std::make_shared<Config>());
 
+  /**
+   * Set deserializer method for type.
+   * @param classId - &id:oatpp::data::mapping::type::ClassId;.
+   * @param method - `typedef AbstractObjectWrapper (*DeserializerMethod)(Deserializer*, parser::Caret&, const Type* const)`.
+   */
   void setDeserializerMethod(const data::mapping::type::ClassId& classId, DeserializerMethod method);
 
+  /**
+   * Deserialize text.
+   * @param caret - &id:oatpp::parser::Caret;.
+   * @param type - &id:oatpp::data::mapping::type::Type;
+   * @return - `AbstractObjectWrapper` over deserialized object.
+   */
   AbstractObjectWrapper deserialize(parser::Caret& caret, const Type* const type);
 
+  /**
+   * Get deserializer config.
+   * @return
+   */
   const std::shared_ptr<Config>& getConfig();
 
 };
diff --git a/src/oatpp/parser/json/mapping/Serializer.hpp b/src/oatpp/parser/json/mapping/Serializer.hpp
index 2f42d5de..ae6d0c00 100644
--- a/src/oatpp/parser/json/mapping/Serializer.hpp
+++ b/src/oatpp/parser/json/mapping/Serializer.hpp
@@ -151,12 +151,30 @@ private:
   std::vector<SerializerMethod> m_methods;
 public:
 
+  /**
+   * Constructor.
+   * @param config - serializer config.
+   */
   Serializer(const std::shared_ptr<Config>& config = std::make_shared<Config>());
 
+  /**
+   * Set serializer method for type.
+   * @param classId - &id:oatpp::data::mapping::type::ClassId;.
+   * @param method - `typedef void (*SerializerMethod)(Serializer*, data::stream::ConsistentOutputStream*, const data::mapping::type::AbstractObjectWrapper&)`.
+   */
   void setSerializerMethod(const data::mapping::type::ClassId& classId, SerializerMethod method);
 
+  /**
+   * Serialize object to stream.
+   * @param stream - &id:oatpp::data::stream::ConsistentOutputStream;.
+   * @param polymorph - DTO as &id:oatpp::data::mapping::type::AbstractObjectWrapper;.
+   */
   void serializeToStream(data::stream::ConsistentOutputStream* stream, const data::mapping::type::AbstractObjectWrapper& polymorph);
 
+  /**
+   * Get serializer config.
+   * @return
+   */
   const std::shared_ptr<Config>& getConfig();
 
 };
diff --git a/test/oatpp/parser/json/mapping/DeserializerTest.hpp b/test/oatpp/parser/json/mapping/DeserializerTest.hpp
index b3d140c5..2173ce3d 100644
--- a/test/oatpp/parser/json/mapping/DeserializerTest.hpp
+++ b/test/oatpp/parser/json/mapping/DeserializerTest.hpp
@@ -32,7 +32,7 @@ namespace oatpp { namespace test { namespace parser { namespace json { namespace
 class DeserializerTest : public UnitTest{
 public:
   
-  DeserializerTest():UnitTest("TEST[parser::json::mapping::DeserializerTestTest]"){}
+  DeserializerTest():UnitTest("TEST[parser::json::mapping::DeserializerTest]"){}
   void onRun() override;
   
 };