Improve Type-Safe Casting with Pattern Matching (#2990)

# Description of Changes

Please provide a summary of the changes, including:

This PR refactors multiple instances of type casting throughout the
codebase by replacing them with Java's pattern matching for
`instanceof`. This approach eliminates redundant type casting, improves
code readability, and reduces the chances of `ClassCastException`. The
changes primarily affect authentication handling, PDF processing, and
certificate validation.

### Key Changes:
- Replaced traditional `instanceof` checks followed by explicit casting
with pattern matching.
- Improved readability and maintainability of type-related operations.
- Applied changes across security modules, PDF utilities, and image
processing functions.

This refactor does not introduce new functionality but enhances the
robustness and clarity of the existing code.

pending until #2818 is published

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#6-testing)
for more details.

src/main/java/stirling/software/SPDF/controller/api/misc/AutoSplitPdfController.java

@@ -61,8 +61,8 @@ public class AutoSplitPdfController {
     private static String decodeQRCode(BufferedImage bufferedImage) {
         LuminanceSource source;
 
-        if (bufferedImage.getRaster().getDataBuffer() instanceof DataBufferByte) {
-            byte[] pixels = ((DataBufferByte) bufferedImage.getRaster().getDataBuffer()).getData();
+        if (bufferedImage.getRaster().getDataBuffer() instanceof DataBufferByte dataBufferByte) {
+            byte[] pixels = dataBufferByte.getData();
             source =
                     new PlanarYUVLuminanceSource(
                             pixels,
@@ -73,8 +73,9 @@ public class AutoSplitPdfController {
                             bufferedImage.getWidth(),
                             bufferedImage.getHeight(),
                             false);
-        } else if (bufferedImage.getRaster().getDataBuffer() instanceof DataBufferInt) {
-            int[] pixels = ((DataBufferInt) bufferedImage.getRaster().getDataBuffer()).getData();
+        } else if (bufferedImage.getRaster().getDataBuffer()
+                instanceof DataBufferInt dataBufferInt) {
+            int[] pixels = dataBufferInt.getData();
             byte[] newPixels = new byte[pixels.length];
             for (int i = 0; i < pixels.length; i++) {
                 newPixels[i] = (byte) (pixels[i] & 0xff);
@@ -91,7 +92,8 @@ public class AutoSplitPdfController {
                             false);
         } else {
             throw new IllegalArgumentException(
-                    "BufferedImage must have 8-bit gray scale, 24-bit RGB, 32-bit ARGB (packed int), byte gray, or 3-byte/4-byte RGB image data");
+                    "BufferedImage must have 8-bit gray scale, 24-bit RGB, 32-bit ARGB (packed"
+                            + " int), byte gray, or 3-byte/4-byte RGB image data");
         }
 
         BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
@@ -108,7 +110,10 @@ public class AutoSplitPdfController {
     @Operation(
             summary = "Auto split PDF pages into separate documents",
             description =
-                    "This endpoint accepts a PDF file, scans each page for a specific QR code, and splits the document at the QR code boundaries. The output is a zip file containing each separate PDF document. Input:PDF Output:ZIP-PDF Type:SISO")
+                    "This endpoint accepts a PDF file, scans each page for a specific QR code, and"
+                        + " splits the document at the QR code boundaries. The output is a zip file"
+                        + " containing each separate PDF document. Input:PDF Output:ZIP-PDF"
+                        + " Type:SISO")
     public ResponseEntity<byte[]> autoSplitPdf(@ModelAttribute AutoSplitPdfRequest request)
             throws IOException {
         MultipartFile file = request.getFileInput();

src/main/java/stirling/software/SPDF/controller/api/misc/CompressController.java

@@ -63,8 +63,7 @@ public class CompressController {
                 if (res != null && res.getXObjectNames() != null) {
                     for (COSName name : res.getXObjectNames()) {
                         PDXObject xobj = res.getXObject(name);
-                        if (xobj instanceof PDImageXObject) {
-                            PDImageXObject image = (PDImageXObject) xobj;
+                        if (xobj instanceof PDImageXObject image) {
                             BufferedImage bufferedImage = image.getImage();
 
                             int newWidth = (int) (bufferedImage.getWidth() * scaleFactor);
@@ -119,7 +118,8 @@ public class CompressController {
     @Operation(
             summary = "Optimize PDF file",
             description =
-                    "This endpoint accepts a PDF file and optimizes it based on the provided parameters. Input:PDF Output:PDF Type:SISO")
+                    "This endpoint accepts a PDF file and optimizes it based on the provided"
+                        + " parameters. Input:PDF Output:PDF Type:SISO")
     public ResponseEntity<byte[]> optimizePdf(@ModelAttribute OptimizePdfRequest request)
             throws Exception {
         MultipartFile inputFile = request.getFileInput();
@@ -221,7 +221,8 @@ public class CompressController {
             // Check if optimized file is larger than the original
             if (pdfBytes.length > inputFileSize) {
                 log.warn(
-                        "Optimized file is larger than the original. Returning the original file instead.");
+                        "Optimized file is larger than the original. Returning the original file"
+                            + " instead.");
                 finalFile = tempInputFile;
             }