How to use additional syntax files?

[AndrzejB]

In https://kate-editor.org/syntax/data/syntax/ (or https://invent.kde.org/frameworks/syntax-highlighting/-/tree/master/data/syntax) is 362 xml files, but I notice that very known Antlr g4 format is not in this set.

I interested in Antlr and want add xml for it.
How can editor based on QPlainTextEdit and using syntax from KF5/KSyntaxHighlighting or even Kate or KWriter use additional syntax definitions in xml files?
How to contribute to https://invent.kde.org with my syntax file?

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Solution:
put to (share)/org.kde.syntax-highlighting/syntax my file

m_repository.addCustomSearchPath(QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation) + QStringLiteral("/org.kde.syntax-highlighting/syntax"));
m_repository.reload();

contribution: fork and pull request