Deprecate StringUtils.concatenate in favor of JDK String.join

[elharo]

fixes #347

[Copilot]

Pull request overview

This PR deprecates the StringUtils.concatenate() method and suggests using Java's built-in String.join() method as a replacement. However, there is a discrepancy between the PR description (which references issue #349 about deprecating StringUtils.clean) and the actual changes (which deprecate StringUtils.concatenate).

Changes:

• Added @Deprecated annotation to the concatenate(Object... array) method
• Added @deprecated javadoc tag suggesting String.join() as replacement

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[Copilot]

The deprecation message has a malformed HTML code tag. The opening parenthesis is inside the code tag but the closing parenthesis is outside it, making it read as "java.lang.String.join(" followed by ") instead". Based on other deprecation patterns in this file (lines 210, 460, 475, 502, 574, 605), the message should either be:

• "use {@code java.lang.String.join()}" (using {@code} format without tags)
• "use java.lang.String.join()" (with both parentheses inside the tag)

The current format with the unmatched parenthesis is inconsistent and will not render correctly in generated documentation.

[Copilot]

The suggested replacement with String.join() is potentially misleading. The StringUtils.concatenate() method accepts Object[] (varargs) and calls toString() on each element, while String.join() requires CharSequence elements. This means String.join() is not a drop-in replacement for cases where non-CharSequence objects are passed.

Consider clarifying the deprecation message to indicate that elements should be converted to strings first, or suggest using a stream-based approach like: Arrays.stream(array).map(Object::toString).collect(Collectors.joining(""))

This is particularly important since the method signature explicitly accepts Object... array, suggesting it was designed to handle non-string objects.

[github-actions]

@elharo Please assign appropriate label to PR according to the type of change.