Make something similar to Acrobat when Underline annotation has no appearance

src/core/annotation.js

@@ -4230,15 +4230,16 @@ class UnderlineAnnotation extends MarkupAnnotation {
           : [0, 0, 0];
         const strokeAlpha = dict.get("CA");
 
+        // The values 0.571 and 1.3 below corresponds to what Acrobat is doing.
         this._setDefaultAppearance({
           xref,
-          extra: "[] 0 d 1 w",
+          extra: "[] 0 d 0.571 w",
           strokeColor,
           strokeAlpha,
           pointsCallback: (buffer, points) => {
             buffer.push(
-              `${points[2].x} ${points[2].y} m`,
+              `${points[2].x} ${points[2].y + 1.3} m`,
-              `${points[3].x} ${points[3].y} l`,
+              `${points[3].x} ${points[3].y + 1.3} l`,
               "S"
             );
             return [points[0].x, points[1].x, points[3].y, points[1].y];

test/pdfs/.gitignore

@@ -589,3 +589,4 @@
 !issue16278.pdf
 !copy_paste_ligatures.pdf
 !issue16316.pdf
+!issue14565.pdf

test/test_manifest.json

@@ -7572,5 +7572,13 @@
       "link": true,
       "forms": true,
       "type": "eq"
+   },
+   {
+      "id": "issue14565",
+      "file": "pdfs/issue14565.pdf",
+      "md5": "ee0b064d227fe90a4795ff0c4dd0a47c",
+      "rounds": 1,
+      "annotations": true,
+      "type": "eq"
    }
 ]