Bugfix/135 receipt validation

[harsha-amarasiri]

Pull Request Description

Fixes AS4 Receipt XML Schema validation issue : OxalisCommunity/Oxalis-AS4#135

• Adds XML schema validation for AS4 receipts against EBMSv3, CEF eDelivery and PEPPOL specifications
• Implements PEPPOL AS4 profile conformance validation for receipts including:
  • NonRepudiationInformation element presence check
  • MessagePartNRInformation validation
  • <ds:Reference> and <ebbp:MessagePartIdentifier> mutual exclusivity (AS4 Profile §5.1.9)
• Provides configurable validation modes: NONE, LOGGING (default), STRICT
• Thread-safe schema validator factory with caching
• Comprehensive test coverage with valid/invalid message samples

Key components:

• SchemaValidatorFactory - Extensible, thread-safe XSD based validation with schema caching
• PeppolAs4ReceiptValidator - PEPPOL-specific conformance rules
• As4ReceiptValidationInInterceptor - CXF interceptor with configurable validation modes
• Configuration: oxalis.as4.receipt.validation (values: none, logging, strict)

Design rationale:

• Isolated and transparent validation - does not break existing flows
• DOM parsing and XPath for precise validation against specifications

Backward compatibility:

• Default behavior: validation errors are logged but do not block transmission
• Operators can enable strict validation via configuration if desired
• No breaking changes to existing AS4 message flows

Type of Pull Request

• New feature/Enhancement - non-breaking change which adds functionality
• Bug fix
• Breaking change (Require Major version change?)

Type of Change

• OpenPeppol eDEC Specifications
• Peppol AS4 Profile specification
• Peppol Business Envelope specification
• Peppol Policies specification
• Peppol eDEC Code Lists specification
• OpenPeppol Spring/Fall release
• Oxalis software internal change or enhancement
• General change

Pull Request Checklist:

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas. But did not add unnecessary annotation/comment say @author name etc
• I have checked my code for variable and method name and corrected grammar/spelling mistakes if any
• I have made corresponding changes to the documentation where needed
• My changes generate no new/additional warnings
• My change is not breaking or creating conflict with associated dependencies
• I have performed a self-review of my own code
• I ran mvn clean install before commit and all tests run successfully
• I conducted basic QA to assure all features are working fine
• My pull request generate no conflicts with master branch
• I requested code review from other team members