protected function generateRequestBody($src)
	{
		$params = [
			'compilation_level' => $this->compilationLevel,
			'js_code'           => $src,
			'output_format'     => 'json',
			'output_info'       => 'compiled_code'
		];

		// Add our custom externs if default externs are disabled
		if ($this->excludeDefaultExterns && $this->compilationLevel === 'ADVANCED_OPTIMIZATIONS')
		{
			$params['exclude_default_externs'] = 'true';
			$params['js_externs'] = $this->externs;
		}

		// Add dupe variables by hand
		$body = http_build_query($params) . '&output_info=errors';

		return $body;
	}