If the IExtractorInvokeOptions.messageCallback sets this property to true, it will prevent the message from being displayed by API Extractor.
messageCallback routes the message to a custom handler (e.g. a toolchain logger), it should assign
handled = true to prevent API Extractor from displaying it. Assigning
handled = true for all messages would effectively disable all console output from the
handled is set to true, the message will still be included in the count of errors/warnings; to discard a message entirely, instead assign
logLevel = none.