PHP 7 Compatibility

I ran the PHP Compatibility Checker plugin https://ww.wp.xz.cn/plugins/php-compatibility-checker/
checking for PHP 7 compatibility and got this result for this plugin:

FILE: wp-content/plugins/stout-google-calendar/gcalendar-wrapper.php
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FOUND 2 ERRORS AFFECTING 2 LINES
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 24 | ERROR | The use of long predefined variables has been deprecated in 5.3 and removed in 5.4; Found '$HTTP_SERVER_VARS'
 25 | ERROR | The use of long predefined variables has been deprecated in 5.3 and removed in 5.4; Found '$HTTP_SERVER_VARS'
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FILE: wp-content/plugins/stout-google-calendar/stout-gc-widget.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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 36 | WARNING | Use of deprecated PHP4 style class constructor is not supported since PHP 7.
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FILE: wp-content/plugins/stout-google-calendar/JSON.php
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FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
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 133 | WARNING | Use of deprecated PHP4 style class constructor is not supported since PHP 7.
 783 | WARNING | Use of deprecated PHP4 style class constructor is not supported since PHP 7.
 797 | WARNING | Use of deprecated PHP4 style class constructor is not supported since PHP 7.
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