stringify UTF-8 to fix PHP warning
stringify UTF-8 to fix PHP warning

Without the quotes, produces warning: 
Warning: htmlspecialchars(): charset `-8' not supported, assuming utf-8 in ... on line ...

And then fatal error:
Fatal error: Uncaught exception 'RuntimeException' with message 'Unable to emit response; headers already sent' ...
acelaya/zend-expressive,moderndeveloperllc/zend-expressive,nightlinus/zend-expressive,ezimuel/zend-expressive,weierophinney/zf-docs-toolchain-experiment,zf2timo/zend-expressive