src/Base/Logger/StdioLogger.php
public function warning($message, array $context = array(), $traceShift = 0)
    {
        $this->log(LogLevel::WARNING, $message, $context, $traceShift);
    }
public function warning($message, array $context = array(), $traceShift = 0)
    {
        $this->log(LogLevel::WARNING, $message, $context, $traceShift);
    }
Exceptional occurrences that are not errors.

Example: Use of deprecated APIs, poor use of an API, undesirable things
that are not necessarily wrong.

@param string|mixed $message
@param array        $context
@param int          $traceShift

@return void