Properly handle multi-line comments split with the newline character (#17)

* Properly handle multi-line comments split with the newline character
* Don't discard trailing newlines
* Add unit tests

configlib-core/src/main/java/de/exlll/configlib/CommentNodeExtractor.java

@@ -95,11 +95,13 @@ final class CommentNodeExtractor {
             final Deque<String> elementNameStack
     ) {
         if (element.isAnnotationPresent(Comment.class)) {
-            final var comments = element.getAnnotation(Comment.class).value();
+            final var comments = Arrays.stream(element.getAnnotation(Comment.class).value())
+                    .flatMap(s -> Arrays.stream(s.split("\n", -1)))
+                    .toList();
             final var formattedName = nameFormatter.format(elementName);
             final var elementNames = new ArrayList<>(elementNameStack);
             elementNames.add(formattedName);
-            final var result = new CommentNode(Arrays.asList(comments), elementNames);
+            final var result = new CommentNode(comments, elementNames);
             return Optional.of(result);
         }
         return Optional.empty();

configlib-core/src/test/java/de/exlll/configlib/CommentNodeExtractorTest.java

@@ -70,6 +70,88 @@ class CommentNodeExtractorTest {
         assertTrue(nodes.isEmpty());
     }
 
+    @Test
+    void extractSingleCommentMultipleLines() {
+        @Configuration
+        class A {
+            @Comment("""
+                    Hello
+                    World""")
+            int i;
+        }
+
+        Queue<CommentNode> nodes = EXTRACTOR.extractCommentNodes(new A());
+        assertEquals(cn(List.of("Hello", "World"), "i"), nodes.poll());
+        assertTrue(nodes.isEmpty());
+    }
+
+    @Test
+    void extractSingleCommentMultipleLinesTrailingNewlines() {
+        @Configuration
+        class A {
+
+            @Comment("""
+                    
+                    
+                    Hello
+                    
+                    World
+                    
+                    
+                    """)
+            int i;
+
+        }
+
+        Queue<CommentNode> nodes = EXTRACTOR.extractCommentNodes(new A());
+        assertEquals(cn(List.of("", "", "Hello", "", "World", "", "", ""), "i"), nodes.poll());
+        assertTrue(nodes.isEmpty());
+    }
+
+    @Test
+    void extractSingleCommentMultipleLinesInArrayAndNewlineSplit() {
+        @Configuration
+        class A {
+
+            @Comment({ """
+                    Hello
+                    World""", """
+                    Hi
+                    Again""" })
+            int i;
+
+        }
+
+        Queue<CommentNode> nodes = EXTRACTOR.extractCommentNodes(new A());
+        assertEquals(cn(List.of("Hello", "World", "Hi", "Again"), "i"), nodes.poll());
+        assertTrue(nodes.isEmpty());
+    }
+
+    @Test
+    void extractSingleCommentMultipleLinesInArrayAndNewlineSplitWithTrailingNewlines() {
+        @Configuration
+        class A {
+
+            @Comment({ """
+                    
+                    Hello
+                    World
+                    
+                    """, """
+                    
+                    Hi
+                    Again
+                    
+                    """ })
+            int i;
+
+        }
+
+        Queue<CommentNode> nodes = EXTRACTOR.extractCommentNodes(new A());
+        assertEquals(cn(List.of("", "Hello", "World", "", "", "", "Hi", "Again", "", ""), "i"), nodes.poll());
+        assertTrue(nodes.isEmpty());
+    }
+
     @Test
     void extractMultipleComments() {
         @Configuration