Add null-safe condition in UnknownFieldsSupport, tweak java-docs, remove unused import

Author: kobylynskyi

src/main/java/com/kobylynskyi/graphql/codegen/mapper/RequestResponseDefinitionToDataModelMapper.java

@@ -29,7 +29,6 @@
 import static com.kobylynskyi.graphql.codegen.model.DataModelFields.GENERATED_ANNOTATION;
 import static com.kobylynskyi.graphql.codegen.model.DataModelFields.GENERATED_INFO;
 import static com.kobylynskyi.graphql.codegen.model.DataModelFields.GENERATE_ALL_METHOD_IN_PROJECTION;
-import static com.kobylynskyi.graphql.codegen.model.DataModelFields.GENERATE_SEALED_INTERFACES;
 import static com.kobylynskyi.graphql.codegen.model.DataModelFields.JAVA_DOC;
 import static com.kobylynskyi.graphql.codegen.model.DataModelFields.METHOD_NAME;
 import static com.kobylynskyi.graphql.codegen.model.DataModelFields.OPERATION_NAME;

src/main/java/com/kobylynskyi/graphql/codegen/mapper/UnknownFieldsSupport.java

@@ -24,7 +24,7 @@ public interface UnknownFieldsSupport {
      *         the instance of {@link ParameterDefinition}. {@link Optional#empty()} otherwise.
      */
     default Optional<ParameterDefinition> createUnknownFields(MappingContext mappingContext) {
-        if (mappingContext.isSupportUnknownFields()) {
+        if (Boolean.TRUE.equals(mappingContext.isSupportUnknownFields())) {
             ParameterDefinition unknownFields = new ParameterDefinition();
             unknownFields.setName(mappingContext.getUnknownFieldsPropertyName());
             unknownFields.setOriginalName(mappingContext.getUnknownFieldsPropertyName());

src/main/java/com/kobylynskyi/graphql/codegen/model/builders/JavaDocBuilder.java

@@ -25,6 +25,9 @@ private JavaDocBuilder() {
      * Get java doc from description of the definition and it's extensions.
      * If no description is present in the definition and extension then return from comments
      *
+     * @param extendedDefinition Extended GraphQL definition
+     * @param <T>                base type
+     * @param <E>                extension type
      * @return List of java docs
      */
     public static <T extends NamedNode<T>, E extends T> List<String> build(
@@ -39,6 +42,9 @@ public static <T extends NamedNode<T>, E extends T> List<String> build(
     /**
      * Get java doc from description for the given definition
      *
+     * @param extendedDefinition Extended GraphQL definition
+     * @param <T>                base type
+     * @param <E>                extension type
      * @return List of java docs
      */
     public static <T extends NamedNode<T>, E extends T> List<String> buildFromDescription(
@@ -65,6 +71,9 @@ public static <T extends NamedNode<T>, E extends T> List<String> buildFromDescri
     /**
      * Get java doc from comments for the given definition
      *
+     * @param extendedDefinition Extended GraphQL definition
+     * @param <T>                base type
+     * @param <E>                extension type
      * @return List of java docs
      */
     public static <T extends NamedNode<T>, E extends T> List<String> buildFromComments(