diff --git a/src/main/java/com/kobylynskyi/graphql/codegen/mapper/FieldDefinitionToParameterMapper.java b/src/main/java/com/kobylynskyi/graphql/codegen/mapper/FieldDefinitionToParameterMapper.java
index 09283ed82e1f3bd6fb03f1f724b4540786c612bc..5de363dfc1288d9139d910efa1a0a45bfa71b2dd 100644
--- a/src/main/java/com/kobylynskyi/graphql/codegen/mapper/FieldDefinitionToParameterMapper.java
+++ b/src/main/java/com/kobylynskyi/graphql/codegen/mapper/FieldDefinitionToParameterMapper.java
@@ -21,7 +21,7 @@ public class FieldDefinitionToParameterMapper {
      * @param mappingConfig    Global mapping configuration
      * @param fieldDefinitions List of GraphQL field definitions
      * @param parentTypeName   Name of the parent GraphQL type
-     * @return Freemarker data model of the GraphQL interface
+     * @return Freemarker data model of the GraphQL field definition
      */
     public static List<ParameterDefinition> map(MappingConfig mappingConfig,
                                                 List<FieldDefinition> fieldDefinitions,
diff --git a/src/main/java/com/kobylynskyi/graphql/codegen/mapper/GraphqlTypeToJavaTypeMapper.java b/src/main/java/com/kobylynskyi/graphql/codegen/mapper/GraphqlTypeToJavaTypeMapper.java
index 137a17ec9c54db070e9f6e41825135317e0a55f8..924f9de37333322389722334b92fe40e9394c785 100644
--- a/src/main/java/com/kobylynskyi/graphql/codegen/mapper/GraphqlTypeToJavaTypeMapper.java
+++ b/src/main/java/com/kobylynskyi/graphql/codegen/mapper/GraphqlTypeToJavaTypeMapper.java
@@ -155,10 +155,28 @@ class GraphqlTypeToJavaTypeMapper {
         return annotations;
     }
 
+    /**
+     * Wrap java type into collection. E.g.: "String" becomes "Collection<String"
+     *
+     * @param type Anything that will be wrapped into Collection<>
+     * @return String wrapped into Collection<>
+     */
     private static String wrapIntoJavaCollection(String type) {
         return String.format("Collection<%s>", type);
     }
 
+    /**
+     * Wraps type into subscriptionReturnType (defined in the mapping configuration.
+     * Example:
+     * Given GraphQL schema:                           type Subscription { eventsCreated: [Event!]! }
+     * Given subscriptionReturnType in mapping config: org.reactivestreams.Publisher
+     * Return: org.reactivestreams.Publisher<Event>
+     *
+     * @param mappingConfig  Global mapping configuration
+     * @param javaTypeName   The type that will be wrapped into
+     * @param parentTypeName Name of the parent type
+     * @return Java type wrapped into the subscriptionReturnType
+     */
     static String wrapIntoSubscriptionIfRequired(MappingConfig mappingConfig, String javaTypeName, String parentTypeName) {
         if (parentTypeName.equalsIgnoreCase(Operation.SUBSCRIPTION.name())
                 && !Utils.isBlank(mappingConfig.getSubscriptionReturnType())) {
diff --git a/src/main/java/com/kobylynskyi/graphql/codegen/mapper/InputValueDefinitionToParameterMapper.java b/src/main/java/com/kobylynskyi/graphql/codegen/mapper/InputValueDefinitionToParameterMapper.java
index b0ed48b18c0b09f915cba155ea850ad55260daee..a61cf3881a47a144d27d734175f312645c88c58b 100644
--- a/src/main/java/com/kobylynskyi/graphql/codegen/mapper/InputValueDefinitionToParameterMapper.java
+++ b/src/main/java/com/kobylynskyi/graphql/codegen/mapper/InputValueDefinitionToParameterMapper.java
@@ -15,6 +15,14 @@ import java.util.stream.Collectors;
  */
 public class InputValueDefinitionToParameterMapper {
 
+    /**
+     * Map input value definition to a Freemarker-understandable data model type
+     *
+     * @param mappingConfig    Global mapping configuration
+     * @param valueDefinitions List of GraphQL value definitions
+     * @param parentTypeName   Name of the parent GraphQL type
+     * @return Freemarker data model of the GraphQL input value definition
+     */
     public static List<ParameterDefinition> map(MappingConfig mappingConfig, List<InputValueDefinition> valueDefinitions, String parentTypeName) {
         if (valueDefinitions == null) {
             return Collections.emptyList();