src/Common/Internal/ServiceRestProxy.php
protected function addMetadataHeaders(array $headers, array $metadata)
    {
        $this->validateMetadata($metadata);

        $metadata = $this->generateMetadataHeaders($metadata);
        $headers = array_merge($headers, $metadata);

        return $headers;
    }
protected function addMetadataHeaders(array $headers, array $metadata)
    {
        $this->validateMetadata($metadata);

        $metadata = $this->generateMetadataHeaders($metadata);
        $headers = array_merge($headers, $metadata);

        return $headers;
    }
protected function addMetadataHeaders ( array $ headers , array $ metadata ) { $ this -> validateMetadata ( $ metadata ) ; $ metadata = $ this -> generateMetadataHeaders ( $ metadata ) ; $ headers = array_merge ( $ headers , $ metadata ) ; return $ headers ; }
Adds metadata elements to headers array.

@param array $headers  HTTP request headers
@param array $metadata user specified metadata

@return array
Adds metadata elements to headers array .