Add support for RegEx expressions in event WebSocket topic filter

[florian-h05]

Closes #4600.

This extends the topic filter for the event WebSocket to support RegEx in addition to the existing * wildcard expressions.
This works by:

1. Checking if a filter topic matches the existing syntax, optionally including the * wildcard
2. Assuming the a filter topic is a RegEx if it does not match in 1.
3. If Pattern Compilation fails, throw an EventProcessingException as previously when a filter topic was invalid.

[florian-h05]

When updating the docs after this has been merged, don’t forget to correct the docs, that the * wildcard does match multiple topic segments.

[kaikreuzer]

@florian-h05 Could you please rebase this PR?

[Copilot]

Pull request overview

This PR extends the event WebSocket topic filter to support regular expressions in addition to the existing wildcard (*) pattern matching. The implementation introduces a TopicFilterMapper class that determines whether a topic filter is a simple pattern (using word characters, slashes, and optional asterisks) or a regular expression. Simple patterns are converted to regex with wildcard expansion and anchoring, while regex patterns are used directly. The change refactors the filter processing logic from EventWebSocket into the new mapper class, improves error handling by passing PatternSyntaxException through the chain, and adds comprehensive test coverage for the new regex functionality.

Key Changes

• Introduced TopicFilterMapper class to handle conversion of topic expressions to regex patterns, supporting both simple wildcard syntax and full regex
• Extended TopicEventFilter constructor to declare PatternSyntaxException for better error transparency
• Added comprehensive test cases covering regex patterns in both include and exclude topic filters

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
TopicFilterMapper.java	New class that maps topic filter expressions to TopicEventFilter, handling both simple wildcard patterns and regex patterns
TopicEventFilter.java	Updated constructor to declare PatternSyntaxException and corrected JavaDoc
EventWebSocket.java	Refactored topic filter logic to use TopicFilterMapper instead of inline processing
EventProcessingException.java	Added constructor accepting both message and cause for better exception chaining
EventWebSocketTest.java	Enhanced tests to cover regex patterns in both include and exclude filters

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[florian-h05]

@kaikreuzer Done