migrate export doclet to Java 17

pom.xml

@@ -51,8 +51,8 @@
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.1</version>
                 <configuration>
-                    <source>1.9</source>
-                    <target>1.9</target>
+                    <source>17</source>
+                    <target>17</target>
                 </configuration>
             </plugin>
             <plugin>

src/main/java/org/asciidoctor/ExportDoclet.java

@@ -39,9 +39,50 @@ public String getName() {
         return "ExportDoclet";
     }
 
+    private boolean includeCaptions = false;
+
     @Override
     public Set<? extends Option> getSupportedOptions() {
-        return new StandardDoclet().getSupportedOptions();
+        Option[] options = {
+                new Option() {
+                    private final List<String> someOption = Arrays.asList(
+                            "--captions",
+                            "-cp"
+                    );
+
+                    @Override
+                    public int getArgumentCount() {
+                        return 1;
+                    }
+
+                    @Override
+                    public String getDescription() {
+                        return "include captions in output";
+                    }
+
+                    @Override
+                    public Option.Kind getKind() {
+                        return Kind.STANDARD;
+                    }
+
+                    @Override
+                    public List<String> getNames() {
+                        return someOption;
+                    }
+
+                    @Override
+                    public String getParameters() {
+                        return "boolean";
+                    }
+
+                    @Override
+                    public boolean process(String opt, List<String> arguments) {
+                        includeCaptions = arguments.get(0).equalsIgnoreCase("true");
+                        return true;
+                    }
+                }
+        };
+        return new HashSet<>(Arrays.asList(options));
     }
 
     @Override
@@ -51,6 +92,6 @@ public SourceVersion getSupportedSourceVersion() {
 
     @Override
     public boolean run(DocletEnvironment environment) {
-        return new ExportRenderer(environment).render();
+        return new ExportRenderer(environment, includeCaptions).render();
     }
 }

src/main/java/org/asciidoctor/ExportRenderer.java

@@ -15,7 +15,6 @@
  */
 package org.asciidoctor;
 
-import com.sun.javadoc.*;
 import jdk.javadoc.doclet.*;
 
 import javax.lang.model.element.*;
@@ -40,9 +39,15 @@ public class ExportRenderer {
      * From this root all other program structure information can be extracted.
      */
     private final DocletEnvironment rootDoc;
+    private final boolean includeCaptions;
 
     public ExportRenderer(DocletEnvironment rootDoc){
+        this(rootDoc, false);
+    }
+
+    public ExportRenderer(DocletEnvironment rootDoc, boolean includeCaptions){
         this.rootDoc = rootDoc;
+        this.includeCaptions = includeCaptions;
     }
 
     /**
@@ -91,7 +96,7 @@ private void renderPackage(Element packageElement){
     }
 
     private void renderEnclosedElements(Element rootElement, PrintWriter writer) {
-        outputText(rootElement, writer);
+        outputText(rootElement, writer, 1);
 
         renderRootElements(new HashSet<>(rootElement.getEnclosedElements()));
 
@@ -100,20 +105,20 @@ private void renderEnclosedElements(Element rootElement, PrintWriter writer) {
         subElements.removeAll(ElementFilter.packagesIn(rootElement.getEnclosedElements()));
 
         for(Element subElement : subElements) {
-            outputText(subElement, writer);
+            outputText(subElement, writer, 2);
         }
 
         writer.flush();
     }
 
     private void outputText(List<? extends Element> elements, PrintWriter writer) {
         for (Element element : elements) {
-            outputText(element.getSimpleName().toString(), rootDoc.getElementUtils().getDocComment(element), writer);
+            outputText(element.getSimpleName().toString(), rootDoc.getElementUtils().getDocComment(element), writer, 2);
         }
     }
 
-    private void outputText(Element element, PrintWriter writer) {
-        outputText(element.getSimpleName().toString(), rootDoc.getElementUtils().getDocComment(element), writer);
+    private void outputText(Element element, PrintWriter writer, int level) {
+        outputText(element.getSimpleName().toString(), rootDoc.getElementUtils().getDocComment(element), writer, level);
     }
 
     /**
@@ -124,10 +129,14 @@ private void outputText(Element element, PrintWriter writer) {
      * @param comment the javadoc comment to export
      * @param writer the link:PrintWriter[] to be used to export the javadoc comment to an AsciiDoc file
      */
-    private void outputText(String tag, String comment, PrintWriter writer) {
+    private void outputText(String tag, String comment, PrintWriter writer, int level) {
         writer.println("// tag::" + tag + "[]");
+        if (includeCaptions) {
+            writer.println(String.format("%s %s", ("=".repeat(level)), tag));
+        }
         writer.println(cleanJavadocInput(comment));
         writer.println("// end::" + tag + "[]");
+        writer.println();
     }
 
     private String cleanJavadocInput(String input) {