fix(verify-pdf): verification to properly detect non-PDF/A documents with XMP metadata (#5397)

# Description of Changes

Fixed an issue where PDFs containing XMP metadata but lacking PDF/A
identification schema were incorrectly being validated as PDF/A
documents and reporting "PDF/A-1b with errors" instead of "NOT PDF/A".

### Changes Made
- Improved the PDF/A detection logic in `VeraPDFService.java` to check
for both missing XMP metadata and missing PDF/A identification schema
- Added validation for clause 6.7.11 (PDF/A Identification extension
schema requirement) in addition to clause 6.7.2 (XMP metadata presence)
- Documents with XMP metadata but without proper PDF/A identification
now correctly return "NOT PDF/A"

### Root Cause
The previous implementation only checked for missing XMP metadata
(clause 6.7.2) but didn't verify that the XMP contained the required
PDF/A identification schema (clause 6.7.11). This caused documents with
generic XMP metadata to be incorrectly treated as declared PDF/A files.

Fixes issue where non-PDF/A documents with XMP metadata were incorrectly
showing PDF/A validation errors.









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---

## Checklist

### General

- [X] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [X] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/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/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [X] I have performed a self-review of my own code
- [X] 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/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

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

### Testing (if applicable)

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

Signed-off-by: Balázs Szücs <bszucs1209@gmail.com>

app/core/src/main/java/stirling/software/SPDF/service/VeraPDFService.java

@@ -204,11 +204,65 @@ public class VeraPDFService {
             detectedFlavours = detectionParser.getFlavours();
         }
 
+        // For PDF/A flavours, we need to validate first to check if PDF/A identification exists in
+        // XMP
+        // If declaredFlavour is PDF/A, do a quick validation to check for PDF/A identification
+        // schema
+        boolean hasValidPdfaMetadata = false;
+        if (isPdfaFlavour(declaredFlavour)) {
+            try (PDFAParser quickParser =
+                    Foundries.defaultInstance()
+                            .createParser(new ByteArrayInputStream(pdfBytes), declaredFlavour)) {
+                PDFAValidator quickValidator =
+                        Foundries.defaultInstance().createValidator(declaredFlavour, false);
+                ValidationResult quickResult = quickValidator.validate(quickParser);
+
+                // Check if the document has the PDF/A Identification extension schema (clause
+                // 6.7.11, test 1)
+                // OR if it lacks XMP metadata entirely (clause 6.7.2, test 1)
+                // If either of these errors is present, the document is NOT a declared PDF/A
+                hasValidPdfaMetadata = true;
+                for (TestAssertion assertion : quickResult.getTestAssertions()) {
+                    if (assertion.getStatus() == TestAssertion.Status.FAILED
+                            && assertion.getRuleId() != null) {
+                        String clause = assertion.getRuleId().getClause();
+                        int testNumber = assertion.getRuleId().getTestNumber();
+
+                        // Missing XMP metadata entirely (clause 6.7.2, test 1)
+                        if ("6.7.2".equals(clause) && testNumber == 1) {
+                            hasValidPdfaMetadata = false;
+                            log.debug(
+                                    "Document lacks XMP metadata (6.7.2): {}",
+                                    assertion.getMessage());
+                            break;
+                        }
+
+                        // Missing PDF/A identification schema in XMP (clause 6.7.11, test 1)
+                        if ("6.7.11".equals(clause) && testNumber == 1) {
+                            hasValidPdfaMetadata = false;
+                            log.debug(
+                                    "Document lacks PDF/A identification in XMP (6.7.11): {}",
+                                    assertion.getMessage());
+                            break;
+                        }
+                    }
+                }
+            } catch (Exception e) {
+                log.debug("Error checking for PDF/A identification: {}", e.getMessage());
+                hasValidPdfaMetadata = false;
+            }
+        }
+
         List<PDFAFlavour> flavoursToValidate = new ArrayList<>();
-        boolean hasPdfaDeclaration = isPdfaFlavour(declaredFlavour);
+        boolean hasPdfaDeclaration = isPdfaFlavour(declaredFlavour) && hasValidPdfaMetadata;
 
         if (declaredFlavour != null) {
-            flavoursToValidate.add(declaredFlavour);
+            boolean isDeclaredPdfa = isPdfaFlavour(declaredFlavour);
+            if (isDeclaredPdfa && hasPdfaDeclaration) {
+                flavoursToValidate.add(declaredFlavour);
+            } else if (!isDeclaredPdfa) {
+                flavoursToValidate.add(declaredFlavour);
+            }
         }
 
         for (PDFAFlavour flavour : detectedFlavours) {