PHP Parse error: syntax error, unexpected '=', expecting ')'

[fabiobatalha]

I'm building a docker image for OTS.

Testing the image, while parsing the references the given error is raised.

ots_1    | PHP Parse error:  syntax error, unexpected '=', expecting ')' in /project/ots/module/ReferencesConversion/src/ReferencesConversion/Model/Converter/References.php on line 445

I'm not an expert in PHP, but it seems it is not a valid sintaxe in PHP 5.4.16

ots/module/ReferencesConversion/src/ReferencesConversion/Model/Converter/References.php

Lines 444 to 447 in 7900ecc

	// comply to crossref's good manners by including mailto parameter in the query
	if (!empty($mailto = $this->config['crossref_api']['mailto'])) {
	$uri .= '&mailto=' . urlencode($mailto);
	}