adding back java8 compatibility

Author: janheise

src/main/java/com/github/joschi/jadconfig/documentation/ConfigurationDocsGenerator.java

@@ -6,7 +6,6 @@
 import com.github.joschi.jadconfig.documentation.printers.ConfigurationSection;
 import com.github.joschi.jadconfig.documentation.printers.CsvDocsPrinter;
 import com.github.joschi.jadconfig.documentation.printers.DocsPrinter;
-import jakarta.annotation.Nonnull;
 import org.apache.commons.lang3.ClassUtils;
 
 import java.io.FileWriter;
@@ -26,7 +25,6 @@ static void main(String[] args) throws IOException {
         generator.generateDocumentation(parseDocumentationFormat(args), ConfigurationBeansSPI::loadConfigurationBeans);
     }
 
-    @Nonnull
     private static DocumentationFormat parseDocumentationFormat(String[] args) {
         if (args.length != 2) {
             throw new IllegalArgumentException("This command needs two arguments - a format and file path. For example" + "csv ${project.build.directory}/configuration-documentation.csv");
@@ -88,7 +86,6 @@ private static ConfigurationSection beanToConfigSections(Object configurationBea
         return new ConfigurationSection(sectionHeading, sectionDescription, sortedSections, entriesWithoutSection);
     }
 
-    @Nonnull
     private static List<ConfigurationSection> sectionsFromEntries(List<ConfigurationEntryWithSection> entries) {
         final Collection<ConfigurationSection> sections = entries.stream()
                 .filter(ConfigurationEntryWithSection::hasSection)
@@ -97,7 +94,6 @@ private static List<ConfigurationSection> sectionsFromEntries(List<Configuration
                 .sorted(Comparator.comparing(ConfigurationSection::hasPriority, Comparator.reverseOrder())).toList();
     }
 
-    @Nonnull
     private static List<ConfigurationEntry> getEntriesWithoutSection(List<ConfigurationEntryWithSection> entries) {
         return entries.stream()
                 .filter(e -> !e.hasSection())